histedit: Show file names in multiple line format

parser: fix crash by parsing "()" in keyword argument position A tree node can be either None or a tuple because x=("group", None) is reduced to x[1].

repoview: introduce a `experimental.extra-filter-revs` config The option define revisions to additionally filter out of all repository "view". The end goal is to provide and easy to way to serve multiple subset of the same repository using multiple "shares". The simplest use case of this feature is to have one view serving the public changesets and one view also serving the draft. This is currently achievable using the new `server.view` option introduced recently by Joerg Sonnenberger. However, more advanced use cases need more advanced definitions. For example some needs a view dedicated to some release branches, or view that hides security fixes to be released. Joerg Sonnenberger and I discussed this topic at the recent mini-sprint and the both of us have seen real life use cases for this. (This series got written during the same mini-sprint). The feature is fully functional, and use similar cache-fallback mechanism to ensure decent performance. However,there remaining room to ensure each share caches and hooks collaborate with each others. This will come at a later time once users start to actually test this feature on real usecase.

copies: filter out copies from non-existent source later in _chain() _changesetforwardcopies() repeatedly calls _chain(). That is very expensive because _chain() does lookups in the manifest. I hope to split up the function in two parts: 1) simple chaining, not considering end points, and 2) filter out files that don't exist in the end points (and ping-pong copies/renames). This patches gets us closer to that by moving the check for non-existent source later in the function. Now there are no more checks for "src" and "dst" in the first loop; all the filtering of invalid copies is done in the second loop. The code also looks much more consistent now. No measureable impact on `hg debugpathcopies 4.0 4.8`. That shouldn't be surprising since the only case we're doing more checks now is in case of chained copies/renames, which are quire rare in practice. Differential Revision: https://phab.mercurial-scm.org/D6277