When <pkg>_DIR is set to an incorrect version we search again and store
the result in the variable, even if it is <pkg>_DIR-NOTFOUND.

There was a bug in the case when the new search does not find anything
and the old value came from a cache entry with UNINITALIZED type.  The
command used to try to load a package configuration file from the last
place searched, and would leave the old wrong value in the entry.  This
commit fixes the behavior to avoid trying to load a missing file and to
set the value to <pkg>_DIR-NOTFOUND as expected.