distro info does not have any retry mecanism

[ssbarnea]

As seen on https://softwarefactory-project.io/logs/84/17184/4/gate/dlrn-api-functional-centos-7/9a7f89d/job-output.txt.gz#_2019-12-12_08_44_02_713195 it can really happen to get a failure due to the intermittent nature of networking.

503 is one of those HTTP codes which are retriable.

2019 | centos-7 | ok: Runtime: 0:00:10.007190
2019 | 
2019 | TASK [Build some packages with DLRN, using --order]
2019 | centos-7 | Traceback (most recent call last):
2019 | centos-7 |   File "/home/zuul-worker/src/softwarefactory-project.io/.venv/bin/dlrn", line 10, in <module>
2019 | centos-7 |     sys.exit(main())
2019 | centos-7 |   File "/home/zuul-worker/src/softwarefactory-project.io/.venv/lib/python2.7/site-packages/dlrn/shell.py", line 178, in main
2019 | centos-7 |     dev_mode=options.dev)
2019 | centos-7 |   File "/home/zuul-worker/src/softwarefactory-project.io/.venv/lib/python2.7/site-packages/dlrn/drivers/rdoinfo.py", line 109, in getpackages
2019| centos-7 |     pkginfo =inforepo.get_info(apply_tag=tags)
2019 | centos-7 |   File "/home/zuul-worker/src/softwarefactory-project.io/.venv/lib/python2.7/site-packages/distroinfo/info.py", line 61, in get_info
2019| centos-7 |     raw_infos = self.fetcher.fetch(*selfinfo_files)
2019 | centos-7 |   File "/home/zuul-worker/src/softwarefactory-project.io/.venv/lib/python2.7/site-packages/distroinfo/fetch.py", line 82, in fetch
2019 | centos-7 |     remote_info=remote_info)
2019 | centos-7 |   File "/home/zuul-worker/src/softwarefactory-project.io/.venv/lib/python2.7/site-packages/distroinfo/fetch.py", line 70, in fetch
2019| centos-7 |info = self.get_file_data(ifn)
2019 | centos-7 |   File "/home/zuul-worker/src/softwarefactory-project.io/.venv/lib/python2.7/site-packages/distroinfo/fetch.py", line 46, in get_file_data
2019 | centos-7 |     content = self.get_file_content(fn)
2019 | centos-7 |   File "/home/zuul-worker/src/softwarefactory-project.io/.venv/lib/python2.7/site-packages/distroinfo/fetch.py", line 152, in get_file_content
2019 | centos-7 |     text = self.fetch_file(fn)
2019 | centos-7 |   File "/home/zuul-worker/src/softwarefactory-project.io/.venv/lib/python2.7/site-packages/distroinfo/fetch.py", line 139, in fetch_file
2019 | centos-7 |     code=req.status_code, reason=req.reason, url=url)
2019 | centos-7 | distroinfo.exception.RemoteFetchError: Failed to fetch remote file: 503 Backend unavailable, connection timeout https://raw.githubusercontent.com/redhat-openstack/rdoinfo/master/tags.yml
2019 | centos-7 | ERROR
2019 | centos-7 | {
2019 | centos-7 |   "delta": "0:00:02.203543",
2019 | centos-7 |   "end": "2019-12-12 08:44:02.738470",
2019 | centos-7 |   "msg": "non-zero return code",
2019 | centos-7 |   "rc": 1,
2019 | centos-7 |   "start": "2019-12-12 08:44:00.534927"
2019 | centos-7 | }

The tool should retry at least 3 times with some delay in between before failing.