git-remote-mediawiki: make error message more precise

In subroutine parse_command, error messages were not correct. For the "import"
function, having too much or incorrect arguments displayed both
"invalid arguments", while it displayed "too many arguments" for the "option"
functions under the same conditions.
Separate the two error messages in both cases.

Signed-off-by: Célestin Matte <celestin.matte@ensimag.fr>
Signed-off-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/mw-to-git/git-remote-mediawiki.perl

@@ -161,12 +161,16 @@ sub parse_command {
 		die("Too many arguments for list\n") if (defined($cmd[2]));
 		mw_list($cmd[1]);
 	} elsif ($cmd[0] eq 'import') {
-		die("Invalid arguments for import\n")
-		    if ($cmd[1] eq EMPTY || defined($cmd[2]));
+		die("Invalid argument for import\n")
+		    if ($cmd[1] eq EMPTY);
+		die("Too many arguments for import\n")
+		    if (defined($cmd[2]));
 		mw_import($cmd[1]);
 	} elsif ($cmd[0] eq 'option') {
+		die("Invalid arguments for option\n")
+		    if ($cmd[1] eq EMPTY || $cmd[2] eq EMPTY);
 		die("Too many arguments for option\n")
-		    if ($cmd[1] eq EMPTY || $cmd[2] eq EMPTY || defined($cmd[3]));
+		    if (defined($cmd[3]));
 		mw_option($cmd[1],$cmd[2]);
 	} elsif ($cmd[0] eq 'push') {
 		mw_push($cmd[1]);