Revert "If saving to a git repository fails, don't create oddly named XML file"

This reverts commit e70bbb637e1d

Linus' solution in commit 27c36ec4cf41 ("Improved handling of git syntax
names with no git repository") is much better and makes my hack
unnecessary.

save-xml.c

@@ -606,12 +606,7 @@ int save_dives_logic(const char *filename, const bool select_only)
 	git = is_git_repository(filename, &branch);
 	if (git)
 		return git_save_dives(git, branch, select_only);
-	/* if the syntax is for a git save but saving we didn't find a
-	 * repository, throw error */
-	if (strchr(filename, '[')) {
-		report_error("Save failed, invalid git repository %s", filename);
-		return -1;
-	}
+
 	try_to_backup(filename);
 
 	save_dives_buffer(&buf, select_only);