Build failures without a build log

[Rebecca N. Palmer]

(If this is an already known problem, where should I have checked before 
reporting it?  If it should be a bug report, against what?)

Several packages say they failed to build, but do not have the build log 
that would normally accompany this.

Of the ones I uploaded recently (pandas, snakemake, statsmodels, theano):
pandas/arm64, armhf, ppc64el (with roughly the normal build duration)
statsmodels/armhf, ppc64el, s390x (s390x with an unusually long build 
duration)
theano/ppc64el, s390x (with short build durations)
The same packages built successfully on Debian, but theano appears to be 
BD-Uninstallable on Ubuntu.

 From the excuses "missing build" list:
dochelp/ppc64el
h5py/ppc64el
mate-applets/s390x
ghc/armhf
These are all less than 24 hours old (the builds, the ghc package is 
older); I didn't find any older ones but I didn't check every entry.

https://bugs.launchpad.net/launchpad/+bug/1621833 suggests this has 
happened before, but that was several years ago and in a PPA.

pandas/s390x has a log that says success but shows a status of fail:
https://launchpad.net/ubuntu/+source/pandas/0.25.3+dfsg2-5/+build/19843276
https://launchpadlibrarian.net/493880134/buildlog_ubuntu-groovy-s390x.pandas_0.25.3+dfsg2-5_BUILDING.txt.gz