Fix test.sh when reusing a running test container
Fix test.sh when reusing a running test container

Without this fix, reusing a running test container fails like this:
```
[...]
+ [[ 2 == 3 ]]
+ [[ fedora == centos ]]
+ docker exec -ti atomic-reactor-fedora-28-py2 rm -rf /tmp/osbs-client
+ docker exec -ti atomic-reactor-fedora-28-py2 dnf builddep -y /tmp/osbs-client/osbs-client.spec
Last metadata expiration check: 2:34:59 ago on Wed Jun 27 11:39:33 2018.
Failed to open: '/tmp/osbs-client/osbs-client.spec', not a valid spec file: can't parse specfile

Error: Some packages could not be found.
```

projectatomic/atomic-reactor,DBuildService/atomic-reactor,fr34k8/atomic-reactor,DBuildService/atomic-reactor,projectatomic/atomic-reactor,fr34k8/atomic-reactor