hook: add a 'hashook' function to test for hook existence Preparing the data for some hooks can be expensive. Add a function to check if a hook exists so we can skip useless preparation if no hook is configured.

build: for the bootstrap phase of a deb/rpm build pure-py mercurial is enough When bootstrapping a deb/rpm build, packagelib.sh starts performing a local build for the sole purpose of parsing the output of "hg version". Then it "hg archive"s the source code, and builds everything again. For that initial step, we are perfectly good in using a pure python mercurial, without compiling the c modules (base85, bdiff, zstdlib, ...). On my personal system, this cuts down 22 seconds for a package build (the bootstrapping build goes from ~30 to ~8 seconds).

context: add a fast-comparision for arbitraryfilectx and workingfilectx Differential Revision: https://phab.mercurial-scm.org/D1056

tersestatus: avoid modifying tersedict Turn dirnode's methods into generators which can be used to update "tersedict" in caller. So instead of passing the "tersedict" to be mutated here and there, it's now clearer where it is updated as it's purely a local variable to tersedir() function. While I was here, I renamed _processtersestatus to tersewalk and _addfilestotersed to iterfilepaths. Differential Revision: https://phab.mercurial-scm.org/D1043

tersestatus: make methods part of the dirnode class Differential Revision: https://phab.mercurial-scm.org/D1042

tersestatus: re-implement the functionality to terse the status The previous terse status implementation was hacking around os.listdir() and was flaky. There have been a lot of instances of mercurial buildbots failing and google's internal builds failing because of the hacky implementation of terse status. Even though I wrote the last implementation but it was hard for me to find the reason for the flake. The new implementation can be slower than the old one but is clean and easy to understand. In this we create a node object for each directory and create a tree like structure starting from the root of the working copy. While building the tree like structure we store some information on the nodes which will be helpful for deciding later whether we can terse the dir or not. Once the whole tree is build we traverse and built the list of files for each status with required tersing. There is no behaviour change as the old test, test-status-terse.t passes with the new implementation. Differential Revision: https://phab.mercurial-scm.org/D985