A timeout doesn't make sense on this level, because it is very difficult
to estimate how long downloading rpm metadata takes. Drop it completely
in favor of higher-level timeouts in the test runner.
Fixes#601
os.Exit() doesn't execute defer-ed functions, OTOH we call panic()
in case of setup errors, which does run defer-ed functions. So move
the actual test setup and execution in a separate function which will
execute all defer-ed functions and return the exit code from the
test suite to TestMain.
The mock server used by unit tests is slightly different than the
running server, mostly related to package names that are hard-coded.
This adds a bool to testState that can be used in the tests to alter the
expected behavior. It should be used as little as possible.
