use correct path in rel-eng/packages if package reside in git-root

if package reside in subdirectory, then in metadata file is written
  1.0 foo/
but if the package reside in git-root, then in metadata file is written
  1.0 /
which is not relative path and if it is evaluated by some tool, it is evaluated incorrectly
This patch will change this singularity to:
  1.0 ./