[RFC PATCH] rev-list: clarify --abbrev and --abbrev-commit usage

Indicate that --abbrev only works with --abbrev-commit also specified. It seems that simply running `git rev-list --abbrev=5` doesn't abbreviate commit OIDs. But the combination of `git rev-list --abbrev-commit --abbrev=5` works as expected. Clarify in the documentation by indicating that --abbrev is an optional addition to the --abbrev-commit option. --no-abbrev remains on a separate line as it can still be used to disable OID abbreviation even if --abbrev-commit has been specified.

Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
Change-Id: If9b1198938e1a3515ae6740241f7b791fb7a88bd
---
I thought this was odd when I was working on the other rev-list changes
- --abbrev doesn't do anything on its own. It looks like it does work by
itself in other commands, but apparently not in rev-list.

Listed this patch as RFC because maybe instead it's better to fix something so --abbrev can be used alone, or teach --abbrev-commit=<n>. It looks like `git log --abbrev=5` also doesn't work the way one might expect, which makes sense to me, as they use the same internals for option parsing (parse_revisions()).

The manpages for log and rev-list both correctly indicate that --abbrev=<n> is an optional addition to --abbrev-commit. `git log -h` is generated by parse-options tooling and doesn't cover --abbrev-commit at all, but `git rev-list` doesn't use an option parser on its own and the usage is hardcoded.

 - Emily

 builtin/rev-list.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)