convert/gnuarch: keep track of original revision in extra headers It seems to be standard to populate the .rev attribute of a commit to keep track of original SCM revision names. Just do it(tm).

convert/gnuarch: robustify cat-log retrieval GNU Arch used to scale very poorly when revision number was increasing. This was mostly caused by the huge amount of cat-log it has to scan/read through to keep track of all patches that were merged in a given revision. In order to improve things, cat-log prunning was a common admin task that would accelerate cat-log parsing at the expense of unreachabe locally stored cat-logs. However, these missing cat-logs are still available in the archive. So try to get them from the archive as a fallback solution.

convert/gnuarch: set prefered locale for str conversions Seems necessary, as a test on my archives goes further with this.

convert/gnuarch: fix cat-log parsing cat-log parsing was very wrong. It assumed the Summary header was comming last, which is wrong. Plus the code was buggy because it was concatenating all headers in the summary. As parsing GNU Arch isn't trivial, and python email code does it so well... just use that ;-)

convert/gnuarch: remove unused code Debug stuff ? Wipe it.

Merge with crew-stable