Fastest way to find repository heads?

[Stephen J. Turnbull]

Robert Collins writes:
 > On Wed, 2009-07-08 at 23:00 +0200, Jelmer Vernooij wrote:
 > > When talking to a git smart server and trying to figure out which
 > > revisions to fetch, bzr-git has to provide the server with all of the
 > > heads in the repository so that the client and the server can negotiate
 > > which revisions have to be transferred.
 > 
 > last I checked git didn't report all heads; it reports all refs, which
 > is quite different.

That is true.  It's possible to get all heads by asking the garbage
collector, though.