[PATCH 0 of 5] updated subrepo fixes/enhancements

[Edouard Gomez]

Respin of my previous patch series.

I tried to address all comments made by benoit and added
one more bugfix for deeper than one level subrepos.

I tried to sync tests whenever necessary, and i added
two more to show better what my patches try to address.

Patch comments have been boosted a bit to ease the
'why' of the patches.

This is still aimed at crew and stable if possible.