We have since createrepo_c update to 0.16 many broken repositories in OBS,
because createrepo_c may skip rpms and is not failing.

This leads to inconsistent repostiories which basically break installations. 

This is not visible to OBS and neither to the users.

example lines of createrepo_c:

C_CREATEREPOLIB: Critical: Cannot dump XML for rubygem-parser-2_3
(997508f2146125fd1ad896ec7cb6fe94d27fef3ceccb74c339c415e2d76f72e8): 
Forbidden control chars found (ASCII values <32 except 9, 10 and 13).