apply: simplify build_fake_ancestor()

The local variable sha1_ptr in the build_fake_ancestor() function
used to either point at the null_sha1[] (if the ancestor did not
have the path) or at sha1[] (if we read the object name into the
local array), but 7a98869 (apply: get rid of --index-info in favor
of --build-fake-ancestor, 2007-09-17) made the "missing in the
ancestor" case unnecessary, hence sha1_ptr, when used, always points
at the local array.

Get rid of the unneeded variable, and restructure the if/else
cascade a bit to make it easier to read.  There should be no
behaviour change.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/apply.c

@@ -3598,28 +3598,26 @@ static void build_fake_ancestor(struct patch *list, const char *filename)
 	 * worth showing the new sha1 prefix, but until then...
 	 */
 	for (patch = list; patch; patch = patch->next) {
-		const unsigned char *sha1_ptr;
 		unsigned char sha1[20];
 		struct cache_entry *ce;
 		const char *name;
 
 		name = patch->old_name ? patch->old_name : patch->new_name;
 		if (0 < patch->is_new)
 			continue;
-		else if (get_sha1_blob(patch->old_sha1_prefix, sha1))
-			/* git diff has no index line for mode/type changes */
-			if (!patch->lines_added && !patch->lines_deleted) {
-				if (get_current_sha1(patch->old_name, sha1))
-					die("mode change for %s, which is not "
-						"in current HEAD", name);
-				sha1_ptr = sha1;
-			} else
-				die("sha1 information is lacking or useless "
-					"(%s).", name);
-		else
-			sha1_ptr = sha1;
 
-		ce = make_cache_entry(patch->old_mode, sha1_ptr, name, 0, 0);
+		if (!get_sha1_blob(patch->old_sha1_prefix, sha1)) {
+			; /* ok */
+		} else if (!patch->lines_added && !patch->lines_deleted) {
+			/* mode-only change: update the current */
+			if (get_current_sha1(patch->old_name, sha1))
+				die("mode change for %s, which is not "
+				    "in current HEAD", name);
+		} else
+			die("sha1 information is lacking or useless "
+			    "(%s).", name);
+
+		ce = make_cache_entry(patch->old_mode, sha1, name, 0, 0);
 		if (!ce)
 			die(_("make_cache_entry failed for path '%s'"), name);
 		if (add_index_entry(&result, ce, ADD_CACHE_OK_TO_ADD))