A few useful Gettext hacks.
Needs to merge translations from a branch back onto HEAD?
msgmerge -C HEAD.po BRANCH.po HEAD.pot > NEW-HEAD.po mv NEW-HEAD.po HEAD.po
Use HEAD.po as a compendium to make sure you get any translations that might have been done in HEAD. Then migrates BRANCH.po to be up-to-date with HEAD.pot. The output NEW-HEAD.po should then be moved to HEAD.po if the merge happened as planned.