systemd uses 'intltool-update -m' from intltoolize in its 'make check'.
$(top_srcdir)/po/POTFILES.skip contains the name of a generated file (src/core/org.freedesktop.systemd1.policy.in), which will be generated as $(top_builddir)/src/core/org.freedesktop.systemd1.policy.in. If $(builddir)==$(srcdir) than everything works fine. When they are different, there's no way to instruct intltool-update to skip the file. Since the name of the build directory is not known and can be arbitrary, there should be a way to instruct intltool-update to ignore files relative to the $(top_builddir), or something like that. One option would be to turn the file list into a list of globs (**/src/core/org.freedesktop.systemd1.policy.in would work perfectly in our case).