fastannotate: process files as they arrive peer.commandexecutor()'s context manager waits for all responses to arrive in its __exit__() method. We want to process the results as they arrive, so we should do that inside the context manager scope. Note that the futures' result() methods have been replaced to make sure that the command executor's sendcommands() method is called when the first future's result is requested, so we don't need to do that. A minor side-effect is that we can no longer easily tell when the server has started sending us responses, so that long statement was lost. Differential Revision: https://phab.mercurial-scm.org/D4666