protocol: drop unused import of zlib Something weird is happening that breaks pyflakes installed via 'pip install --user'. I haven't had a chance to finish debugging this, but this at least fixes the build.

hook: lower inflated use of sys.__stdout__ and __stderr__ They were introduced at 9f76df0edb7d, where sys.stdout could be replaced by sys.stderr. After that, we've changed the way of stdout redirection by afccc64eea73, so we no longer need to reference the original __stdout__ and __stderr__ objects. Let's move away from using __std*__ objects so we can simply wrap sys.std* objects for Python 3 porting.

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.

dirstate: change added/modified placeholder hash length to 20 bytes Previously the added/modified placeholder hash for manifests generated from the dirstate was a 21byte long string consisting of the p1 file hash plus a single character to indicate an add or a modify. Normal hashes are only 20 bytes long. This makes it complicated to implement more efficient manifest implementations which rely on the hashes being fixed length. Let's change this hash to just be 20 bytes long, and rely on the astronomical improbability of an actual hash being these 20 bytes (just like we rely on no hash every being the nullid). This changes the possible behavior slightly in that the hash for all added/modified entries in the dirstate manifest will now be the same (so simple node comparisons would say they are equal), but we should never be doing simple node comparisons on these nodes even with the old hashes, because they did not accurately represent the content (i.e. two files based off the same p1 file node, with different working copy contents would have the same hash (even with the appended character) in the old scheme too, so we couldn't depend on the hashes period).

dirstate: change placeholder hash length to 20 bytes Previously the new-node placeholder hash for manifests generated from the dirstate was a 21byte long string of "!" characters. Normal hashes are only 20 bytes long. This makes it complicated to implement more efficient manifest implementations which rely on the hashes being fixed length. Let's change this hash to just be 20 bytes long, and rely on the astronomical improbability of an actual hash being 20 "!" bytes in a row (just like we rely on no hash ever being the nullid). A future diff will do this for added and modified dirstate markers as well, so we're putting the new newnodeid in node.py so there's a common place for these placeholders.

util: remove compressorobj API from compression engines All callers have been replaced with "compressstream." It is quite low-level and redundant with "compressstream." So eliminate it.

hgweb: use compression engine API for zlib compression More low-level compression code elimination because we now have nice APIs. This patch also demonstrates why we needed and implemented the "level" option on the "compressstream" API.

bundle2: use compressstream compression engine API Compression engines now have an API for compressing a stream of chunks. Switch to it and make low-level compression code disappear.

util: add a stream compression API to compression engines It is a common pattern throughout the code to perform compression on an iterator of chunks, yielding an iterator of compressed chunks. Let's formalize that as part of the compression engine API. The zlib and bzip2 implementations allow an optional "level" option to control the compression level. The default values are the same as what the Python modules use. This option will be used in subsequent patches.

util: remove decompressors dict (API) All in-tree consumers are now using the compengines registrar. Extensions should switch to it as well.

changegroup: use compression engines API The new API doesn't have the equivalence for None and 'UN' so we introduce code to use 'UN' explicitly.

bundle2: use compression engines API to obtain decompressor Like the recent change for the compressor side, this too is relatively straightforward. We now store a compression engine on the instance instead of a low-level decompressor. Again, this will allow us to easily transition to different compression engine APIs when they are implemented.

util: remove compressors dict (API) We no longer have any in-tree consumers of this object. Use util.compengines instead.