convert: Work around p4 instability (
issue2465)
The p4 command-line client sometimes fails upon doing "p4 describe"
when trying to produce a patch. (I'm guessing it's a bug in p4.)
However, "hg convert" doesn't even make use of the patch, and it can
be elided by adding "-s" to the p4 command line here.
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.