ui: move pre/post processes from low-level write()s to _writenobuf() This helps adding a dedicated stream for status/error messages. I don't want to add _write*() function per stream.

ui: pass in file object to _writenobuf() See the subsequent patches for why. The "if" block in _writenobuf() will be removed soon.

perf: fix perfrevlogrevisions --reverse Currently, 'endrev' equals `len(revlog)`, a revision that does not exist. When asking for the reverse order, the arguments passed to xrange are `xrange(len(revlog), startrev)` which then crash. We need to offset 'endrev' by one so we don't crash anymore. Also, we offset 'startrev' to ensure we get the same number of revisions with and without the `--reverse` option. Differential Revision: https://phab.mercurial-scm.org/D5228

procutil: import concerns about creationflags on Windows from D1701 I don't have the need anymore for the change in D1701 nor the time to investigate the changes on all supported Windows platforms. I import the stuff I learned on D1701 in the `runbgcommand` so the next people working on it can starts from there. Differential Revision: https://phab.mercurial-scm.org/D5229

localrepo: extract loading of hgrc files to standalone function Various 3rd party extensions supplement where per-repo config data lives. Looking at their sources, they resort to unorthodox means to inject the config data. And the way they do it is susceptible to corner cases. e.g. not processing automatic extension loads, not reacting to new or disabled extensions in configs, etc. This commit extracts the core logic of loading hgrc files into a standalone function so there is a clear function that can be monkeypatched to inject per-repo config data at repository open time. Differential Revision: https://phab.mercurial-scm.org/D5221

revsets: make bookmark/named('re:nonexistent') not abort (issue6018) (BC) Foozy documented the differences between revsets branch(), tag(), bookmark(), and named() in eeb5d5ab14a6 (revset: raise RepoLookupError to make present() predicate continue the query, 2015-01-31). He seemed to want tag() to change behavior to not error out on non-matching regular expressions. I think it's instead bookmark() and named() that should not error out. So that's what this patch does. Differential Revision: https://phab.mercurial-scm.org/D5220

fix: rename :fileset subconfig to :pattern This name was always inaccurate, since the config accepts any pattern. Hopefully so few people use this right now that it won't matter, but there will now be a warning if the old config name is used. Differential Revision: https://phab.mercurial-scm.org/D5226

fix: add a config to abort when a fixer tool fails This allows users to stop and address tool failures before proceeding, instead of the default behavior of continuing to apply any tools that didn't fail. For example, a code formatting tool could fail if you have syntax errors, and you might want your repo to stay in its current state while you fix the syntax error before re-running 'hg fix'. It's conceivable that this would even be necessary for the correctness of some fixer tools across a chain of revisions. Differential Revision: https://phab.mercurial-scm.org/D5200

perf: measure slicing time in perfrevlogrevision Slicing a sparse delta chain can be expensive. We now benchmark the associated time.

perf: teach perfrevlogrevision about sparse reading Before this change, chunks were always read in a single block. Even in the sparse-read/sparse-revlog case. This gave a false view of the performance and could lead to memory consumption issue.