Resolve "hammer.py: mitigate timeouts when uploading to nexus"

Closes #2058 (closed)

One commit to fix an indent of 3 spaces instead of 4 please.

Another one with the actual changes. Disable "Show whitespace changes" if you want to only see the latter.

Test run: https://jenkins.aws.isc.org/view/Kea-manual/job/kea-manual/job/pkg/78/