The command module accepts "creates" or "deletes" arguments which
cause it to internally skip running the command if the referenced
path exists or not (as appropriate). This idempotency check is
not implemented as a skipped task since it occurs inside the module
itself. Instead, the module runs normally from Ansible's point of
view and simply returns a message indicating it chose not to run
the command.
This change updates the zuul_stream callback to check for this
message and, if found, terminate the streaming connection immediately
without waiting for any data (as we do for skipped tasks).
Without this, any command or shell task with a creates or deletes
argument would wait 10 seconds for the log stream to terminate.
Change-Id: I352f641368dcfc697be9634f26ce3a8393b96c1b
21be3b2d4b