[PATCH/RFC] commit: add short option for --amend

I just realized how often I type "git ci --amend". Looking back at my
~/.bash_history (only 10k lines) this is the second most often git
command I type which may justify a short option for it (assuming that
other people use this option often too, of course).

The short option space for 'git commit' is really crowded with
acCeFhimnopqsStuvz already taken. So it could be '-M' or '-A' but I'd
prefer not to hold shift, so I chose '-j' even though it's not
strictly related to "amend" (or perhaps we can thinking of amending as
joining commits).

Thoughts?

Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---
 builtin/commit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index 213fca2d8e..78f125ba1f 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c

@@ -1489,7 +1489,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 			    STATUS_FORMAT_LONG),
 		OPT_BOOL('z', "null", &s.null_termination,
 			 N_("terminate entries with NUL")),
-		OPT_BOOL(0, "amend", &amend, N_("amend previous commit")),
+		OPT_BOOL('j', "amend", &amend, N_("amend previous commit")),
 		OPT_BOOL(0, "no-post-rewrite", &no_post_rewrite, N_("bypass post-rewrite hook")),
 		{ OPTION_STRING, 'u', "untracked-files", &untracked_files_arg, N_("mode"), N_("show untracked files, optional modes: all, normal, no. (Default: all)"), PARSE_OPT_OPTARG, NULL, (intptr_t)"all" },
 		/* end commit contents options */

-- 
2.18.0.1004.g6639190530