An element on GIT_CEILING_DIRECTORIES list that does not name the
real path to a directory (i.e. a symbolic link) could have caused
the GIT_DIR discovery logic to escape the ceiling.
* mh/ceiling:
string_list_longest_prefix(): remove function
setup_git_directory_gently_1(): resolve symlinks in ceiling paths
longest_ancestor_length(): require prefix list entries to be normalized
longest_ancestor_length(): take a string_list argument for prefixes
longest_ancestor_length(): use string_list_split()
Introduce new function real_path_if_valid()
real_path_internal(): add comment explaining use of cwd
Introduce new static function real_path_internal()
ce956fc48e