ExtUtils::ParseXS generates nondeterministic C files (differing order) out of .xs files. This leads to differently compiled objects. . There are some code copies, so we have the following bugs in total- https://bugs.debian.org/829295 https://bugs.debian.org/829296 . Fix is also required in ExtUtils::ParseXS in perl(-modules)
Our notes about issues affecting packages are stored in notes.git and are targeted at packages in Debian in 'unstable/amd64' (unless they say otherwise).