tree 1fc613edd34eb349b673505b872be21a416ab52f
parent 0f0dfa3930bc16078ef0b1a00ff6849333038fc7
author Shawn O. Pearce <sop@google.com> 1240092281 -0700
committer Shawn O. Pearce <sop@google.com> 1240092281 -0700

Improve checkout performance for the common unmodified case

Most projects will have their branch heads matching in all branches,
so switching between them should be just a matter of updating the
work tree's HEAD symref.  This can be done in pure Python, saving
quite a bit of time over forking 'git checkout'.

Signed-off-by: Shawn O. Pearce <sop@google.com>