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.
% file replaced with directory
adding a
% should fail - would corrupt dirstate
abort: file 'a' in dirstate clashes with 'a/a'
% directory replaced with file
adding a/a
% should fail - would corrupt dirstate
abort: directory 'a' already in dirstate
% directory replaced with file
adding b/c/d
% should fail - would corrupt dirstate
abort: directory 'b' already in dirstate