diff --relative: help working in a bare repository

This allows the --relative option to say which subdirectory to
pretend to be in, so that in a bare repository, you can say:

    $ git log --relative=drivers/ v2.6.20..v2.6.22 -- drivers/scsi/

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/diff.c b/diff.c
index db4bd557b..2b89b1600 100644
--- a/diff.c
+++ b/diff.c
@@ -2302,6 +2302,10 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		options->detect_rename = 0;
 	else if (!strcmp(arg, "--relative"))
 		DIFF_OPT_SET(options, RELATIVE_NAME);
+	else if (!prefixcmp(arg, "--relative=")) {
+		DIFF_OPT_SET(options, RELATIVE_NAME);
+		options->prefix = arg + 11;
+	}
 
 	/* xdiff options */
 	else if (!strcmp(arg, "-w") || !strcmp(arg, "--ignore-all-space"))