checkout: overwrite files with differing modes

When a file exists on disk and we're checking out a file that differs
in executableness, remove the old file.  This allows us to recreate the
new file with p_open, which will take the new mode into account and
handle setting the umask properly.

Remove any notion of chmod'ing existing files, since it is now handled
by the aforementioned removal and was incorrect, as it did not take
umask into account.

src/checkout.c

@@ -243,6 +243,12 @@ static int checkout_action_common(
 		if (delta->new_file.mode == GIT_FILEMODE_LINK && wd != NULL)
 			*action |= CHECKOUT_ACTION__REMOVE;
 
+		/* if the file is on disk and doesn't match our mode, force update */
+		if (wd &&
+			GIT_PERMS_IS_EXEC(wd->mode) !=
+			GIT_PERMS_IS_EXEC(delta->new_file.mode))
+				*action |= CHECKOUT_ACTION__REMOVE;
+
 		notify = GIT_CHECKOUT_NOTIFY_UPDATED;
 	}
 
@@ -1500,15 +1506,6 @@ static int blob_content_to_file(
 	if (error < 0)
 		return error;
 
-	if (GIT_PERMS_IS_EXEC(mode)) {
-		data->perfdata.chmod_calls++;
-
-		if ((error = p_chmod(path, mode)) < 0) {
-			giterr_set(GITERR_OS, "Failed to set permissions on '%s'", path);
-			return error;
-		}
-	}
-
 	if (st) {
 		data->perfdata.stat_calls++;
 

tests/checkout/tree.c

@@ -996,7 +996,8 @@ mode_t read_filemode(const char *path)
 	git_buf_joinpath(&fullpath, "testrepo", path);
 	cl_must_pass(p_stat(fullpath.ptr, &st));
 
-	result = GIT_PERMS_IS_EXEC(st.st_mode) ? 0100755 : 0100644;
+	result = GIT_PERMS_IS_EXEC(st.st_mode) ?
+		GIT_FILEMODE_BLOB_EXECUTABLE : GIT_FILEMODE_BLOB;
 
 	git_buf_free(&fullpath);