bdiff: give slight preference to removing trailing lines [This change could be folded into the previous changeset to minimize the repo churn ...] Similar to the previous change, introduce an exception to the general preference for matches in the middle of bdiff ranges: If the best match on the B side starts at the beginning of the bdiff range, don't aim for the middle-most A side match but for the earliest. New (later) matches on the A side will only be considered better if the corresponding match on the B side *not* is at the beginning of the range. Thus, if the best (middle-most) match on the B side turns out to be at the beginning of the range, the earliest match on the A side will be used. The bundle size for 4.0 (hg bundle --base null -r 4.0 x.hg) happens to go from 22807275 to 22808120 bytes - a 0.004% increase.

--- a/mercurial/bdiff.c	Tue Nov 15 21:56:49 2016 +0100
+++ b/mercurial/bdiff.c	Tue Nov 15 21:56:49 2016 +0100
@@ -184,7 +184,7 @@
 				mj = j;
 				mk = k;
 			} else if (k == mk) {
-				if (i > mi && i <= half) {
+				if (i > mi && i <= half && j > b1) {
 					/* same match but closer to half */
 					mi = i;
 					mj = j;