RFC: migrating to git

[Simon Marlow]

Thanks to everyone who responded on this thread! It's great to see so 
much feedback.

Of the people who responded, most were in favour of a switch to git, 
with a few notable exceptions.  Here at GHC HQ, I'm slightly in favour 
of switching while Ian and Simon PJ are agnostic.

So, we've decided to try switching to git.  The changeover will be 
staged: first we'll switch the GHC repository, and if all goes well 
we'll switch the libraries and other sub-repositories.  This means we 
can experiment with git for the GHC repo while we establish exactly what 
strategy to use for each sub-repository (change the master to git, or 
leave the master in darcs and mirror).  It does mean for a short while 
GHC developers will have to use two VCS tools, but the sync-all tool 
will hide the difference to some extent.

The next step is to set up the git repo, probably based on the mirror I 
set up last week, and sort out various details (commit emails, 
buildbots, wiki updates etc.).  I'll send out a notification once things 
are set up and we have a date/time for the git repo going live.

Cheers,
	Simon