Test failing on OpenBSD 7.1

[guedou]

The test named Check offline sniff() with a PcapNg file and a filter (by file object) is failing on OpenBSD 7.1 with the following error scapy.error.Scapy_Exception: Failed to compile filter expression udp (-1). I will try to reproduce the issue on a local VM.

Originally posted by @guedou in https://github.com/secdev/scapy/pull/3716#issuecomment-1220521197