The build directory includes the running kernel version if PIKE_BUILD_OS
is not set, as upstream the Makefile uses "uname -s -r -m" set this
valu... resulting in a different build path during the build, which
indirectly changes the buildid of various binaries.

The attached patch to debian/rules fixes this by setting PIKE_BUILD_OS
to the value of DEB_HOST_GNU_TYPE, although any number of other
DEB_HOST_* variables could be used instead while still remaining
reproducible.

Unfortunately, this patch alone does not solve all reproducibility
issues with pike8.0, but applying this patch should significantly reduce
the differences, making it easier to debug remaining issues.

Thanks for maintaining pike8.0!

live well,
  vagrant