convert/cvs: delay CVS log parsing after initialization (issue1581/2) Source and destination constructors should be fast so configurations issues are hit quickly, including authentication and filemap/authormap/splicemap issues. Delaying might be a problem if the remove side disconnects idle connections while the log is being read. It did not happen when converting openafs repository, where log retrieval took at least 10mn.

convert: better mapfile parsing errors (issue1581/1)

Merge with crew-stable

convert/bzr: fix file rename replaced by a dir case (issue1583) We were not checking entry types, and getting file content was working with directories instead of raising IOError.