package creation broken on 5.1-CURRENT

A couple of ports are creating broken bzip2 archives since I updated
the build environments to 5.1-CURRENT:

----
ports-i386%bzip2 -t ja-makejvf-fkr-1.0_1.tbz
bzip2: ja-makejvf-fkr-1.0_1.tbz: file ends unexpectedly

You can use the `bzip2recover' program to attempt to recover
data from undamaged sections of corrupted files.

ports-i386%bzip2 -t cclient-2002c1_1,1.tbz
bzip2: cclient-2002c1_1,1.tbz: file ends unexpectedly

You can use the `bzip2recover' program to attempt to recover
data from undamaged sections of corrupted files.
----

They're broken no matter how many times I rebuild them.  The bento
package cluster machines haven't been updated, so I don't blame a
kernel problem, but the build chroot is being populated with a
5.1-CURRENT world instead of 5.1-RELEASE.

Can anyone else reproduce this, or has anyone else seen a similar
problem?

Kris