unpack-trees: fix accidentally quadratic behavior

While unpacking trees (e.g. during git checkout), when we hit a cache
entry that's past and outside our path, we cut off iteration.

This provides about a 45% speedup on git checkout between master and
master^20000 on Twitter's monorepo.  Speedup in general will depend on
repostitory structure, number of changes, and packfile packing
decisions.

Signed-off-by: David Turner <dturner@twopensource.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

0 files changed, 0 insertions, 0 deletions