0498e29829
We document that this can be disabled by setting the instance_master_path config to "<None>", but don't actually support it in code. oslo.config doesn't actually translate that value to the Python None as we expect. Allow disabling the cache by setting the config to the empty string, as in "instance_master_path=". This doesn't make sense as a directory to use as a cache anyway, so it shouldn't break anyone. Change-Id: I1bb62d55e3e18272fd5da355d63fd2c11a033acd Story: 2004279 Task: 27829