How to sabotage 9.*-RELEASE worldbuilds?

[rank1seeker at gmail.com]

Just do this:
# echo 'FORMATS="html txt"' >> /etc/make.conf

buildworld fails, at the SAME point for ALL 9.*-RELEASE-es:
===========
===> lib/libauditd (all)
===> lib/libcom_err (all)
gzip -cn /usr/src/lib/libcom_err/../../contrib/com_err/com_err.3 > com_err.3.gz
===> lib/libcom_err/doc (all)
Graph cycles through com_err.'html

make: don't know how to make txt'. Stop
*** Error code 2

Stop in /usr/src/lib/libcom_err.
*** Error code 1

Stop in /usr/src/lib.
*** Error code 1

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.
*** Error code 1

Stop in /usr/src.
===========


If you aren't in a mood, to wait for a buildworld to fail, you can see errors faster:
# cd /usr/src && make cleandir > /dev/null
---
"/usr/src/share/mk/bsd.info.mk", line 140: warning: duplicate script for target "txt".gz" ignored
...
---


For /usr/doc builds, in /etc/make.conf, I have:
===========
# For port textproc/docproj
WITH_JADETEX=YES
DOC_LANG="en_US.ISO8859-1"
FORMATS="html txt"
===========


Domagoj Smolčić