v0.5.0

### Breaking changes

* Open commits are now disabled by default. That means that `jj checkout` will
  always create a new change on top of the specified commit and will let you
  edit that in the working copy. Set `ui.enable-open-commits = true` to restore
  the old behavior and let us know that you did so we know how many people
  prefer the workflow with open commits.

* `jj [op] undo` and `jj op restore` used to take the operation to undo or
  restore to as an argument to `-o/--operation`. It is now a positional
  argument instead (i.e. `jj undo -o abc123` is now written `jj undo abc123`).

* An alias that is not configured as a string list (e.g. `my-status = "status"`
  instead of `my-status = ["status"]`) is now an error instead of a warning.

* `jj log` now defaults to showing only commits that are not on any remote
  branches (plus their closest commit on the remote branch for context). This
  set of commits can be overridden by setting `ui.default-revset`. Use
  `jj log -r 'all()'` for the old behavior. Read more about revsets
  [here](https://github.com/martinvonz/jj/blob/main/docs/revsets.md).
  [#250](https://github.com/martinvonz/jj/issues/250)

* `jj new` now always checks out the new commit (used to be only if the parent
  was `@`).

* `jj merge` now checks out the new commit. The command now behaves exactly
  like `jj new`, except that it requires at least two arguments.

* When the working-copy commit is abandoned by `jj abandon` and the parent
  commit is open, a new working-copy commit will be created on top (the open
  parent commit used to get checked out).

* `jj branch` now uses subcommands like `jj branch create` and
  `jj branch forget` instead of options like `jj branch --forget`.
  [#330](https://github.com/martinvonz/jj/issues/330)

* The [`$NO_COLOR` environment variable](https://no-color.org/) no longer
  overrides the `ui.color` configuration if explicitly set.

* `jj edit` has been renamed to `jj touchup`, and `jj edit` is now a new command
  with different behavior. The new `jj edit` lets you edit a commit in the
  working copy, even if the specified commit is closed.

* `jj git push` no longer aborts if you attempt to push an open commit (but it
  now aborts if a commit does not have a description).

* `jj git push` now pushes only branches pointing to the `@` by default. Use
  `--all` to push all branches.

* The `checkouts` template keyword is now called `working_copies`, and
  `current_checkout` is called `current_working_copy`.

### New features

* The new `jj interdiff` command compares the changes in commits, ignoring
  changes from intervening commits.

* `jj rebase` now accepts a `--branch/-b <revision>` argument, which can be used
  instead of `-r` or `-s` to specify which commits to rebase. It will rebase the
  whole branch, relative to the destination. The default mode has changed from
  `-r @` to `-b @`.

* The new `jj print` command prints the contents of a file in a revision.

* The new `jj git remotes list` command lists the configured remotes and their
  URLs.
  [#243](https://github.com/martinvonz/jj/issues/243)

* `jj move` and `jj squash` now lets you limit the set of changes to move by
  specifying paths on the command line (in addition to the `--interactive`
  mode). For example, use `jj move --to @-- foo` to move the changes to file
  (or directory) `foo` in the working copy to the grandparent commit.

* When `jj move/squash/unsquash` abandons the source commit because it became
  empty and both the source and the destination commits have non-empty
  descriptions, it now asks for a combined description. If either description
  was empty, it uses the other without asking.

* `jj split` now lets you specify on the CLI which paths to include in the first
  commit. The interactive diff-editing is not started when you do that.

* Sparse checkouts are now supported. In fact, all working copies are now
  "sparse", only to different degrees. Use the `jj sparse` command to manage
  the paths included in the sparse checkout.

* Configuration is now also read from `~/.jjconfig.toml`.

* The `$JJ_CONFIG` environment variable can now point to a directory. If it
  does, all files in the directory will be read, in alphabetical order.

* The `$VISUAL` environment is now respected and overrides `$EDITOR`. The new
  `ui.editor` config has higher priority than both of them. There is also a new
  `$JJ_EDITOR` environment variable, which has even higher priority than the
  config.

* You can now use `-` and `+` in revset symbols. You used to have to quote
  branch names like `my-feature` in nested quotes (outer layer for your shell)
  like `jj co '"my-feature"'`. The quoting is no longer needed.

* The new revset function `connected(x)` is the same as `x:x`.

* The new revset function `roots(x)` finds commits in the set that are not
  descendants of other commits in the set.

* ssh-agent is now detected even if `$SSH_AGENT_PID` is not set (as long as
  `$SSH_AUTH_SOCK` is set). This should help at least macOS users where
  ssh-agent is launched by default and only `$SSH_AUTH_SOCK` is set.

* When importing from a git, any commits that are no longer referenced on the
  git side will now be abandoned on the jj side as well. That means that
  `jj git fetch` will now abandon unreferenced commits and rebase any local
  changes you had on top.

* `jj git push` gained a `--change <revision>` argument. When that's used, it
  will create a branch named after the revision's change ID, so you don't have
  to create a branch yourself. By default, the branch name will start with
  `push-`, but this can be overridden by the `push.branch-prefix` config
  setting.

* `jj git push` now aborts if you attempt to push a commit without a
  description or with the placeholder "(no name/email configured)" values for
  author/committer.

* Diff editor command arguments can now be specified by config file.
  Example:

      [merge-tools.kdiff3]
      program = "kdiff3"
      edit-args = ["--merge", "--cs", "CreateBakFiles=0"]

* `jj branch` can accept any number of branches to update, rather than just one.

* Aliases can now call other aliases.

* `jj log` now accepts a `--reversed` option, which will show older commits
  first.

* `jj log` now accepts file paths.

* `jj obslog` now accepts `-p`/`--patch` option, which will show the diff
  compared to the previous version of the change.

* The "(no name/email configured)" placeholder value for name/email will now be
  replaced if once you modify a commit after having configured your name/email.

* Color setting can now be overridden by `--color=always|never|auto` option.

* `jj checkout` now lets you specify a description with `--message/-m`.

* `jj new` can now be used for creating merge commits. If you pass more than
  one argument to it, the new commit will have all of them as parents.

### Fixed bugs

* When rebasing a conflict where one side modified a file and the other side
  deleted it, we no longer automatically resolve it in favor of the modified
  content (this was a regression from commit c0ae4b16e8c4).

* Errors are now printed to stderr (they used to be printed to stdout).

* Updating the working copy to a commit where a file's executable bit changed
  but the contents was the same used to lead to a crash. That has now been
  fixed.

* If one side of a merge modified a directory and the other side deleted it, it
  used to be considered a conflict. The same was true if both sides added a
  directory with different files in. They are now merged as if the missing
  directory had been empty.

* When using `jj move` to move part of a commit into an ancestor, any branches
  pointing to the source commit used to be left on a hidden intermediate commit.
  They are now correctly updated.

* `jj untrack` now requires at least one path (allowing no arguments was a UX
  bug).

* `jj rebase` now requires at least one destination (allowing no arguments was a
  UX bug).

* `jj restore --to <rev>` now restores from the working copy (it used to restore
  from the working copy's parent).

* You now get a proper error message instead of a crash when `$EDITOR` doesn't
  exist or exits with an error.

* Global arguments, such as `--at-op=<operation>`, can now be passed before
  an alias.

* Fixed relative path to the current directory in output to be `.` instead of
  empty string.

* When adding a new workspace, the parent of the current workspace's current
  checkout will be checked out. That was always the intent, but the root commit
  was accidentally checked out instead.

* When checking out a commit, the previous commit is no longer abandoned if it
  has a non-empty description.

* All commands now consistently snapshot the working copy (it was missing from
  e.g. `jj undo` and `jj merge` before).