Matt Mackall <mpm@selenic.com> [Sat, 30 Oct 2010 02:47:34 -0500] rev 12890
revlog: choose best delta for parentdelta (issue2466)
When parentdelta is enabled, we choose the delta that has the minimum
distance to its base. Otherwise, base may be sufficiently far away to
require a full version, resulting in greatly reduced compression.