Add workaround for pip install issue

This week, we're seeing plenty of pipelines crashing with

[Errno 99] Cannot assign requested address

during pip install call. This is horrible and we can't seem to find the root cause so far (ipv4/6 switching doesn't seem to be the problem as it's still happening with the changes rolled back). Try to work around the issue by adding retries, same as we use for koji.

Signed-off-by: Veronika Kabatova vkabatov@redhat.com