convert/gnuarch: follow continuation-of revisions Built on top of previous patches: - continuation-of parsing - registered archives retrieval - use of fully qualified revisions This allows the converter scanning for more source revisions following the tree versions 'leaked' through the continuation-of informations. Coupled with the registered archives retrieval, this makes possible to decide to follow such a hint or stop scanning for more revisions. This also implies some changes in the retrieval of some base-0 revisions when they're continuation-of other revisions, in that case a 'replay' will work where a simple 'get' fails because the dir exists already. I found the code dealing with 'replay' quite good as it has already a fallback to 'get' in the error path.

convert/gnuarch: retrieve known archive names list This will make possible in a followup patch to prevent following history that is not reachable because an archive is unknown to the user.

convert/gnuarch: parse continuation-of revisions in gnuarch source In GNU Arch, continuation-of was often used for: - tagging revisions - continue working on a project in a new archive, because arch was scaling poorly in revision numbers (cat-logs were slow to be parsed and scanned through) - very similar to the previous point, fork his own branch of a project. Parsing this header information will allow to 'follow' new history because it often hints at older/forked/personal revision trees. This patch however just implements the parsing of the continuation-of header. A followup patch will implement the proper use of this new information.

convert/gnuarch: use fully qualified revisions There is no need loosing information in the conversion process. This could lead to wrong shamap mappings if different archives used the same 'version' naming.

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.