AttributeError: type object 'ipv4' has no attribute 'ipv4' when parsing ICMP packets

[BonelessPi]

While parsing ICMP packets of type time_exceeded or destination_unreachable, the following error occurs:
AttributeError: type object 'ipv4' has no attribute 'ipv4'

This originates from pox/pox/lib/packet/icmp.py, where the offending code attempts to instantiate an ipv4 object:

from . import ipv4
self.next = ipv4.ipv4(raw=raw[self.MIN_LEN:],prev=self)

The fix would be to replace "ipv4.ipv4" with "ipv4" on lines 182 and 247.
Additionally, a quick scan of icmpv6.py suggests that there may be a similar issue on icmpv6.py line 915.

Related:

• It looks like this was inadvertently caused by the changing of imports in commit 4903eda
• This bug was encountered in this prior issue but then misattributed to user error: ICMP error while processing packets #258