worktree: simplify incompatibility message for --orphan and commit-ish

Use a single translatable string to report that the worktree add option
--orphan is incompatible with a commit-ish instead of having the
commit-ish in a separate translatable string.  This reduces the number
of strings to translate and gives translators the full context.

A similar message is used in builtin/describe.c, but with the plural of
commit-ish, and here we need the singular form.

Signed-off-by: René Scharfe <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: rscharfe

builtin/worktree.c

@@ -815,8 +815,8 @@ static int add(int ac, const char **av, const char *prefix)
 		die(_("options '%s' and '%s' cannot be used together"),
 		    "--orphan", "--no-checkout");
 	if (opts.orphan && ac == 2)
-		die(_("'%s' and '%s' cannot be used together"), "--orphan",
-		    _("<commit-ish>"));
+		die(_("option '%s' and commit-ish cannot be used together"),
+		    "--orphan");
 	if (lock_reason && !keep_locked)
 		die(_("the option '%s' requires '%s'"), "--reason", "--lock");
 	if (lock_reason)