ab/i18n + jl/fetch-submodule-recursive cause failing tests in pu

Just a note: The t5526-fetch-submodules.sh test is failing in pu
because the gettextization of git-submodule conflicts with its tests
assumptions.

It just needs the NO_GETTEXT_POISON prerequisite. I can add that to
ab/i18n once jl/fetch-submodule-recursive is merged to master, or the
other way around, whichever comes first.