So as not to pollute command-line flags with test.* options.
It appears that importing "testing" (from stdlib) will add flags. To
avoid this, we need code to not depend on testing. But, since
testing_utils was previously in the same package as the rest of the
code, it dragged testing in.
Renaming testing_util.go to e.g., util_for_test.go might be enough to
avoid it being compiled with the regular code. We may want it to be
available to tests for other packages -- after all it is utilities for
testing -- so it goes in its own package.
The zone DB no longer considers duplciates of (IP, name); it will
reject duplicates of (IP, name, ident), but this ultimately doesn't
matter since those are all the fields it records anyway.
The HTTP interface treats these duplicates as trivial success (i.e.,
it acts as if it's idempotent, which it is).
This changes the behaviour for removals: if (IP, name) is recorded for
two different containers, removing one will leave the other extant.
Michael Bridgen