[Debian-med-packaging] Bug#710339: python-cogent: FTBFS: failed to remove `doc/_build/html/_images/math/'

[Aaron M. Ucko]

Source: python-cogent
Version: 1.5.3-1
Severity: serious
Justification: fails to build from source (but built successfully in the past)

Builds of python-cogent covering only its architecture-dependent
binary packages (as on the autobuilders) have been failing:

  rmdir doc/_build/html/_images/math/
  rmdir: failed to remove `doc/_build/html/_images/math/': No such file or directory
  make[1]: *** [override_dh_auto_build] Error 1

Could you please clean this directory up only when it actually exists?

Thanks!