Comment 6 for bug 1649814

Here a local build log of the same case with a fix applied:
If looking for apibuild we can see:
  srcdir=../../../docs builddir=. /usr/bin/python2 ../../../docs/apibuild.py
  touch ../../../docs/apibuild.py.stamp
  if [ -x /usr/bin/xsltproc ] ; then \

The fix we have applied makes the apibuild not to fail.
And then it hits:
  touch ../../../docs/apibuild.py.stamp
and goes on as the working bileto build.

It almost seems that in the bileto env there would have been a valid ../../../docs/apibuild.py.stamp around to skip that part - which IMHO should be impossible.