…tive branch

Summary: Ref T13588. See PHI2228. When there is no active branch name (for example, because you are in Git on a detached HEAD), this section currently fails under PHP8 when we try to `strlen(null)`.

Test Plan: Under PHP 8.1: ran `git checkout <hash of head>`, then `arc diff` to generate this revision.

Maniphest Tasks: T13588

Differential Revision: https://secure.phabricator.com/D21856

Summary:
Ref T13588. See PHI2228. Under PHP8.2 and newer, calls to "utf8_decode()" raise a deprecation warning.

The behavior of this function probably isn't great under any PHP version since it UTF8 space into ISO-8859-1 space, which isn't an operation you can really implement "correctly" in the general case. For the specific narrow case of counting characters, as here, you could probably do worse, but I think the PHP upstream's deprecation of this function is entirely reasonable.

The fallback implementation for strlen, "phutil_utf8v()", should produce the correct result in all cases. The downside is that it's runtime UTF8 parsing, which may be slow. This function is called rarely and I don't think this will present a problem, but if it does I'd rather address it once it arises.

Test Plan: Under PHP8.2, ran "arc lint". After patch, no longer saw deprecation warning.

Maniphest Tasks: T13588

Differential Revision: https://secure.phabricator.com/D21857

Summary:
Mercurial 6.4 was recently released and showing up in package managers. With
the update to 6.4 using `arc land` would result in an exception indicating that
`expandpath` function does not exist.

The `ui.expandpath` function was deprecated in 5.8 and now removed in 6.4. The
functionality has been moved to `utils.urlutil.get_` functions (they are split
between getting pull, push, and clone paths).

This updates the script to try `utils.urlutil.get_clone_path` function if the
`ui.expandpath` function is not present.

Test Plan:
I updated my latest mercurial install to 6.4 and verified with `hg --version`.

I created a diff in a mercurial repo and used `arc land` to successfully land
the revision without any exceptions.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D21859

Summary: While testing and updating Phabricator to address PHP 8.2 incompatibilities this diff covers issues that stem from rARC.

Test Plan:
1. Tried to create a diff with invalid diff contents via the web page
2. Run `arc unit --everything`

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D21865

Summary:
Found a few more issues while playing around with `arc`.

Refs T13588

Test Plan:
- Run `arc look` and variants with subcommands
- Run `arc diff` while not on a git branch

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T13588

Differential Revision: https://secure.phabricator.com/D21870