parse-options: recognize abbreviated negated option with arg

Giving an argument to an option that doesn't take one causes Git to
report that error specifically:

   $ git rm --dry-run=bogus
   error: option `dry-run' takes no value

The same is true when the option is negated or abbreviated:

   $ git rm --no-dry-run=bogus
   error: option `no-dry-run' takes no value

   $ git rm --dry=bogus
   error: option `dry-run' takes no value

Not so when doing both, though:

   $ git rm --no-dry=bogus
   error: unknown option `no-dry=bogus'
   usage: git rm [-f | --force] [-n] [-r] [--cached] [--ignore-unmatch]

(Rest of the usage message omitted.)

Improve consistency and usefulness of the error message by recognizing
abbreviated negated options even if they have a (most likely bogus)
argument.  With this patch we get:

   $ git rm --no-dry=bogus
   error: option `no-dry-run' takes no value

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/parse-options.c b/parse-options.c
index 63a99dea6e..e4ce33ea48 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -391,7 +391,7 @@ is_abbreviated:
 					ambiguous_option = abbrev_option;
 					ambiguous_flags = abbrev_flags;
 				}
-				if (!(flags & OPT_UNSET) && *arg_end)
+				if (*arg_end)
 					p->opt = arg_end + 1;
 				abbrev_option = options;
 				abbrev_flags = flags ^ opt_flags;
@@ -412,7 +412,8 @@ is_abbreviated:
 			if (!skip_prefix(arg + 3, long_name, &rest)) {
 				/* abbreviated and negated? */
 				if (allow_abbrev &&
-				    starts_with(long_name, arg + 3))
+				    !strncmp(long_name, arg + 3,
+					     arg_end - arg - 3))
 					goto is_abbreviated;
 				else
 					continue;