Thanks for looking into this. I can offer this which may help:
The file pnwtl/translations/pnlang.vcproj was originally in the main pn repository.
Once Mercurial subrepos were launched I
... [More] moved this file (and the whole translations directory) to translations_old and added a separate project (with files of the same names) as a subrepo mapped to translations.
I would guess this is causing the problem. It may be worth noting that it looks like Mercurial itself has some problems with this, I can't actually regress my history past this point without Mercurial breaking. I plan to file a bug on this! [Less]