Work around weird import error.
Work around weird import error.


Former-commit-id: 4916c9e8c46e79c03aa2a0914b37b141fd440152
projectcalico/libcalico,L-MA/libcalico,plwhite/libcalico,djosborne/libcalico,alexhersh/libcalico,tomdee/libnetwork-plugin,Symmetric/libcalico,TrimBiggs/libnetwork-plugin,TrimBiggs/libcalico,insequent/libcalico,projectcalico/libnetwork-plugin,robbrockbank/libcalico,caseydavenport/libcalico,tomdee/libcalico,TrimBiggs/libnetwork-plugin