File::Copy in Perl 5.10 does not copy permissions, so let's fix it
there and check for it elsewhere.
This reverts the two commits 06b3faa1bf
and 68c20b4e4e which did not help to fix
this issue as the initially suspected noexec mount wasn't really
there. Hopefully this finally resolves the test failures with Perl
5.10 in the new t/hook-apt.t.