hook: flush stdout before redirecting to stderr When hook output redirection is enabled (e.g. when cloning over ssh), hook output on stdout is redirected to stderr, to prevent the repository data on stdout from being corrupted. In certain cases, the redirection could cause part of the repository data to end up on stderr as well. In case of a clone, this causes: "abort: consistency error in delta!" This was seen with a clone over ssh, an outgoing hook present (any non-python type, e.g. 'pwd'), on certain repositories only, probably depending on the distribution of the sent data) This patch updates the hook redirection code to flush stdout before redirecting, removing the problem.