sequencer: avoid using errno clobbered by rollback_lock_file()

As pointed out in a review of the `--rebase-merges` patch series,
`rollback_lock_file()` clobbers errno. Therefore, we have to report the
error message that uses errno before calling said function.

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: dscho

sequencer.c

@@ -346,12 +346,14 @@ static int write_message(const void *buf, size_t len, const char *filename,
 	if (msg_fd < 0)
 		return error_errno(_("could not lock '%s'"), filename);
 	if (write_in_full(msg_fd, buf, len) < 0) {
+		error_errno(_("could not write to '%s'"), filename);
 		rollback_lock_file(&msg_file);
-		return error_errno(_("could not write to '%s'"), filename);
+		return -1;
 	}
 	if (append_eol && write(msg_fd, "\n", 1) < 0) {
+		error_errno(_("could not write eol to '%s'"), filename);
 		rollback_lock_file(&msg_file);
-		return error_errno(_("could not write eol to '%s'"), filename);
+		return -1;
 	}
 	if (commit_lock_file(&msg_file) < 0)
 		return error(_("failed to finalize '%s'"), filename);
@@ -2125,9 +2127,9 @@ static int save_head(const char *head)
 	written = write_in_full(fd, buf.buf, buf.len);
 	strbuf_release(&buf);
 	if (written < 0) {
+		error_errno(_("could not write to '%s'"), git_path_head_file());
 		rollback_lock_file(&head_lock);
-		return error_errno(_("could not write to '%s'"),
-				   git_path_head_file());
+		return -1;
 	}
 	if (commit_lock_file(&head_lock) < 0)
 		return error(_("failed to finalize '%s'"), git_path_head_file());