combine_path() on relative paths with initial '.' fails under some circumstances.
Imported from https://youtrack.roxen.com/issue/PIKE-137
Reported by @grubba
Example:
Pike v8.0 release 702 running Hilfe v3.5 (Incremental Pike Frontend)
> combine_path("./../foo");
(1) Result: "foo"The expected result is "../foo".