This follows up on 5c703aeb0397b560a383bdd57a87235834074b64.
The only reason for this change is that, subjectively, the result looks better to me. I'm not sure why, but I couldn't get used to the old symbol in spite of its seeming reasonableness. It felt really bold and heavy.
If people agree, we can wait until we need to update the screenshots for some other reason before merging this. Sorry I didn't figure this out while the discussion about the referenced commit was going on.
I'm not 100% certain how many fonts support each symbol. Please try it out and let me know if it doesn't work for you.
Compare after:

and before:

@joyously found `o` confusing because it's a valid change id prefix. I
don't have much preference, but `●` seems fine. The "ascii",
"ascii-large", and "legacy" graph styles still use "o".
I didn't change `@` since it seems useful to have that match the
symbol used on the CLI. I don't think we want to have users do
something like `jj co ◎-`.
This eliminates ambiguous parsing between "func()" and "expr ()".
I chose "++" as template concatenation operator in case we want to add
bit-wise negate operator. It's also easier to find/replace than "~".
This allows us to use "if(description,)" to test empty description. And
I think this change is unavoidable if we want to add support for commit
template.
Since CR+LF vs LF things shouldn't matter in commit description, it's probably
better to normalize newline characters.
In Mercurial, ui.edit() and changelog.stripdesc() handle line normalization,
and trailing newlines are stripped. In Git, cleanup_message() handles that,
and the last newline is added after stripping trailing newlines.
Otherwise the description set by -m would differ from the one set by editor.
This fixes test_describe() which says "make no changes", but previously "\n"
would be added by the second "jj describe".
As you can see, almost all hashes change in CLI tests. This means in-flight
PRs will need to be rebased to update insta snapshots.
Description text could be normalized by CommitBuilder, but the caller would
have to normalize it beforehand to compare with the current description, so
we would need an explicit function anyway. Another idea is to add a newtype
that represents a normalized description, and make CommitBuilder require it.
Commit::description() will return &Description in place of &str to ensure
that commit.description() == raw_str wouldn't compile.
Git CLI provides --cleanup=<mode> option to switch normalization rules, but
I don't think we'll need such feature.
Let's acknowledge everyone's contributions by replacing "Google LLC"
in the copyright header by "The Jujutsu Authors". If I understand
correctly, it won't have any legal effect, but maybe it still helps
reduce concerns from contributors (though I haven't heard any
concerns).
Google employees can read about Google's policy at
go/releasing/contributions#copyright.
It seems very likely that we're going to remove support for open
commits, but it's still useful to have a `commit` command that lets
the user enter a description and starts a new change. Calling it
`commit` seems good to make the transition from other VCSs simpler.