clean: consolidate handling of ignored parameters

I spent a long time trying to figure out how and whether the code worked
with different values of ignore, ignore_only, and remove_directories.
After lots of time setting up lots of testcases, sifting through lots of
print statements, and walking through the debugger, I finally realized
that one piece of code related to how it was all setup was found in
clean.c rather than dir.c.  Make a change that would have made it easier
for me to do the extra testing by putting this handling in one spot.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/clean.c

@@ -924,12 +924,6 @@ int cmd_clean(int argc, const char **argv, const char *prefix)
 			     0);
 
 	memset(&dir, 0, sizeof(dir));
-	if (ignored_only)
-		dir.flags |= DIR_SHOW_IGNORED;
-
-	if (ignored && ignored_only)
-		die(_("-x and -X cannot be used together"));
-
 	if (!interactive && !dry_run && !force) {
 		if (config_set)
 			die(_("clean.requireForce set to true and neither -i, -n, nor -f given; "
@@ -946,6 +940,13 @@ int cmd_clean(int argc, const char **argv, const char *prefix)
 
 	dir.flags |= DIR_SHOW_OTHER_DIRECTORIES;
 
+	if (ignored && ignored_only)
+		die(_("-x and -X cannot be used together"));
+	if (!ignored)
+		setup_standard_excludes(&dir);
+	if (ignored_only)
+		dir.flags |= DIR_SHOW_IGNORED;
+
 	if (argc) {
 		/*
 		 * Remaining args implies pathspecs specified, and we should
@@ -960,9 +961,6 @@ int cmd_clean(int argc, const char **argv, const char *prefix)
 	if (read_cache() < 0)
 		die(_("index file corrupt"));
 
-	if (!ignored)
-		setup_standard_excludes(&dir);
-
 	pl = add_pattern_list(&dir, EXC_CMDL, "--exclude option");
 	for (i = 0; i < exclude_list.nr; i++)
 		add_pattern(exclude_list.items[i].string, "", 0, pl, -(i+1));