Make '!' aliases more useful

When an alias starts with an exclamation mark, the rest is interpreted
as a shell command. However, all arguments passed to git used to be
ignored.

Now you can have an alias like

	$ git config alias.e '!echo'

and

	$ git e Hello World

does what you expect it to do.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git.c

@@ -181,6 +181,21 @@ static int handle_alias(int *argcp, const char ***argv)
 	git_config(git_alias_config);
 	if (alias_string) {
 		if (alias_string[0] == '!') {
+			if (*argcp > 1) {
+				int i, sz = PATH_MAX;
+				char *s = xmalloc(sz), *new_alias = s;
+
+				add_to_string(&s, &sz, alias_string, 0);
+				free(alias_string);
+				alias_string = new_alias;
+				for (i = 1; i < *argcp &&
+					!add_to_string(&s, &sz, " ", 0) &&
+					!add_to_string(&s, &sz, (*argv)[i], 1)
+					; i++)
+					; /* do nothing */
+				if (!sz)
+					die("Too many or long arguments");
+			}
 			trace_printf("trace: alias to shell cmd: %s => %s\n",
 				     alias_command, alias_string + 1);
 			ret = system(alias_string + 1);