hook: flush stdout before restoring stderr redirection There was a similar issue to 8b011ededfb2. If an in-process hook writes to stdout, the data may be buffered. In which case, stdout must be flushed before restoring its file descriptor. Otherwise, remaining data would be sent over the ssh wire and corrupts the protocol. Note that this is a different redirection from the one I've just removed.

hook: do not redirect stdout/err/in to ui while running in-process hooks (BC) It was introduced by a59058fd074a to address command-server issues. After that, I've made a complete fix by 69f86b937035, so we don't need to replace sys.stdio objects to protect the IPC channels. This change means we no longer see data written to sys.stdout/err by an in-process hook on command server. I think that's okay because the canonical way is to use ui functions and in-process hooks should respect the Mercurial API. This will help Python 3 porting, where sys.stdout is TextIO but ui.fout is BytesIO.

merge: change modified indicator to be 20 bytes Previously we indicated that the .hgsubstate file was dirty by adding a '+' to the end of its hash in the wctx manifest. This made is complicated to have new manifest implementations that rely on the node length being fixed. In previous patches we added added and modified node placeholders, so let's use those to indicate dirty here as well. It doesn't look like anything ever depended on this '+' (aside from it being different to the parent), so nothing else needed to change here.