[PATCH] parse-options: print "fatal:" before usage_msg_opt()

[Jeff King <peff@peff.net>]

Programs may use usage_msg_opt() to print a brief message
followed by the program usage, and then exit. The message
isn't prefixed at all, though, so it doesn't match our usual
error output and is easy to overlook:

    $ git clone 1 2 3
    Too many arguments.

    usage: git clone [<options>] [--] <repo> [<dir>]

    -v, --verbose         be more verbose
    -q, --quiet           be more quiet
    --progress            force progress reporting
    -n, --no-checkout     don't create a checkout
    --bare                create a bare repository
    [...and so on for another 31 lines...]

It looks especially bad when the message starts with an
option, like:

    $ git replace -e
    -e needs exactly one argument

    usage: git replace [-f] <object> <replacement>
       or: git replace [-f] --edit <object>
    [...etc...]

Let's put our usual "fatal:" prefix in front of it.

Signed-off-by: Jeff King <peff@peff.net>
---
Some of the message in git-clone could stand to be rewritten to match
our usual style, too (no capitals, no trailing period), but that's
obviously out of scope for this patch. I don't think this change makes
them look any worse.

 parse-options.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/parse-options.c b/parse-options.c
index 312a85dbd..4fbe924a5 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -661,7 +661,7 @@ void NORETURN usage_msg_opt(const char *msg,
 		   const char * const *usagestr,
 		   const struct option *options)
 {
-	fprintf(stderr, "%s\n\n", msg);
+	fprintf(stderr, "fatal: %s\n\n", msg);
 	usage_with_options(usagestr, options);
 }
 
-- 
2.11.0.341.g202cd3142