[tlu] Was switching repositories and go this crash

[Maxwell, Adam R]

Apparently the final MacTeX version shipped without a file that tells tlmgr (and, therefore, TLU) what version to expect. There's a workaround here, thanks to Bruno Voisin.

https://github.com/amaxwell/tlutility/issues/17#issuecomment-111517743

I suppose I'll have to add a special case that parses the tlmgr revision number if I get flooded with bug reports.

Adam