Commit f77700aa, which fixes a compiler warning, also breaks the
behaviour of prepending ".<layer>" to basenames in --pxe-service: in
situations where the basename contains a ".", the ".<layer>" suffix is
erroneously added, and in situations where the basename doesn't contain
a ".", the ".<layer>" suffix is erroneously omitted.

A patch against the git HEAD is attached that inverts this logic and
restores the expected behaviour of --pxe-service.