import_logs give a IOError: [Errno 29] Illegal seek when receiving log from pipe

[mattab]

This was an issue reported in forums:
http://forum.piwik.org/read.php?2,111193
http://forum.piwik.org/read.php?2,97108

and a nice pull request to fix it was proposed in https://github.com/piwik/piwik/pull/294/files

To reproduce the issue, type:

$ head test-log.log | ./misc/log-analytics/import_logs.py --add-sites-new-hosts --url='http://localhost/piwik-master/' -

[mattab]

In 7513fef: Merge pull request #294 from etmatrix/master

import_logs give a IOError: 29 Illegal seek when receive log from pipe because we can't seek stdin in pipe mode

Fixes #5254