Set umask to 0002 for ostree operations
See https://github.com/ostreedev/ostree/pull/1984 where OSTree was
changed to try to set group write on directories. We need to set a more
permissive umask to take advantage of it.
This is all done to support writing to the OSTree repo from OpenShift
projects that run as a random UID, but have ftpsync (gid:263) in their
supplemental groups. For more context see: https://pagure.io/releng/issue/8811#comment-629051
Signed-off-by: Mohan Boddu <mboddu@bhujji.com>