How do I clear no-longer-usable packages from poudriere?

I have a local package-builder that's (generally) been working quite
well for me since Jul 2015 (through a couple of hardware replacements,
sure, but the approach remains the same).

Today, in trying to chase down what was causing my central "hub" machine
to whine:

ld-elf.so.1: /usr/local/lib/libtasn1.so.6: version LIBTASN1_0_3 required by /usr/local/lib/libgnutls.so.30 not defined

I found (via the "pkg_libchk" script from ports-mgmt/bsdadminscripts2)
that some just-installed packages are apparently expecting to use
libc.so.6, which hasn't existed on anything here since 18 February.

(My machines run stable/14 for getting things done; the development
machines also track head, so I have some clue what's coming.)

The package-builder also builds FreeBSD for its "client" machines.  The
package-builder (and my laptop) track stable/14 daily; the
package-builder does a 2-pass weekend run of package-building (first
pass on Saturday, after updating FreeBSD; second on Sunday).  Once the
packages are built, the client machines update FreeBSD (to the latest
snapshot from the package-builder, which is already running that code).

The package-builder is thus running the same revision of FreeBSD that
the clients are about to run.  And poudriere is using the
package-builder's /usr/src and /usr/ports to construct jails & build
stuff.

I am trying to ensure a certain level of consistency, here.  And today
appears to show that I have failed to do that.

Is there something less drastic than clearing all poudriere caches of
packages and rebuilding all packages all over again??!? (that will get
me a set of packages consistent with the current state of FreeBSD
sources and ports (stable/14-n266921-8a7d5d73b849 and
main-n654175-6928d3a11398, respectively (at the moment)))?

At least name resolution isn't broken this time, but printing seems to
have been a casualty.

Peace,
david
-- 
David H. Wolfskill                              david@catwhisker.org
Alexey Navalny was a courageous man; Putin has made him a martyr.

See https://www.catwhisker.org/~david/publickey.gpg for my public key.