run-tests: verbose output for `fdroid update` to aid debugging

run-tests: verbose output for `fdroid update` to aid debugging

I'm stumped by this stacktrace, hopefully debug logging will help:

Unknown exception found!
Traceback (most recent call last):
  File "./fdroidserver-0.4.0/fdroid", line 141, in <module>
    main()
  File "./fdroidserver-0.4.0/fdroid", line 119, in main
    mod.main()
  File "<http://localhost:18080/job/fdroidserver/ws/.testfiles/tmp.9hr9NiSmZs/fdroidserver-0.4.0/fdroidserver/update.py",> line 1146, in main
    apks, cachechanged = scan_apks(apps, apkcache, repodirs[0], knownapks)
  File "<http://localhost:18080/job/fdroidserver/ws/.testfiles/tmp.9hr9NiSmZs/fdroidserver-0.4.0/fdroidserver/update.py",> line 543, in scan_apks
    thisinfo['sig'] = getsig(os.path.join(os.getcwd(), apkfile))
  File "<http://localhost:18080/job/fdroidserver/ws/.testfiles/tmp.9hr9NiSmZs/fdroidserver-0.4.0/fdroidserver/update.py",> line 361, in getsig
    with zipfile.ZipFile(apkpath, 'r') as apk:
  File "/usr/lib/python2.7/zipfile.py", line 770, in __init__
    self._RealGetContents()
  File "/usr/lib/python2.7/zipfile.py", line 857, in _RealGetContents
    x._decodeExtra()
  File "/usr/lib/python2.7/zipfile.py", line 388, in _decodeExtra
    tp, ln = unpack('<HH', extra[:4])
struct.error: unpack requires a string argument of length 4