We'll use them in CLI code.

The Display impl helps to format error messages. Since both Regex and
glob::Pattern implement Display, it's probably okay for our type to copy that.

The error message for unmatched patterns is adjusted so that it can be applied
to both exact and glob patterns.

find_forgettable_branches() is unchanged for now. I might want to rewrite it
to not remove untracked remote branches (because untracked branches aren't
associated with the local counterparts.)

The parse rule is lax compared to revset. We could require the pattern to be
quoted, but that would mean glob patterns have to be quoted like 'glob:"foo*"'.

…yntax

I'm not going to remove --glob anytime soon, but I won't add --glob option to
new commands.