[Lib] Fixed a bug in filter_version introduced in a recent commit
[Lib] Fixed a bug in filter_version introduced in a recent commit

b7e0fcba6dc50620528a2be3dd29cc01b2054761 was a bad refactoring job which
added a bug in the network.py filter_version function to make it stop
working right.

fyookball/electrum,fyookball/electrum,fyookball/electrum