build errors on Fedora 24 and CentOS 7

[Lukas Pirl]

Hi Brian and thanks for getting me started with the Tahoe buildbot slaves.

All new slaves seem to be doing now what they are supposed to do.

However, Fedora 24 and CentOS 7 complete with failing tests.

If this is or could be related to the deployment, please let me know.

Also, feel free to put the email address
  tahoe at lukas-pirl.de
in the buildbot slaves' "Admin" field.

Cheers,

Lukas