Do NOT run nosetests directly!

Instead use the top-level Makefile's "tests" target:

  $ make tests

Due to broken shutdown functions in net-snmp, the netsnmpagent test files MUST
each run in new Python interpreter instances. If you run nosetests directly,
a single Python interpreter instance will be used and the netsnmpagent setup
in test_02_netsnmpagent_init.py will sabotage the netsnmpagent setup in
test_03_netsnmpagent_snmpobjs.py.

One way to fix this would be to have nosetests run each test file inside a
separate process, but it's easier to just call nosetests with each test file
separately from a shell loop as done in the top-level Makefile.