scmutil: add utility fn to return repo object with user passed revs unhidden There has been a need for accessing hidden changesets by default without passing --hidden. This is currently done using the directaccess extension but is bit hacky. This patch adds a utility function to return a repo object having user passed revisions unhidden. This functionality will live behind a config option and won't be the default behaviour. There is also a config option added by this patch which tells whether we want to unhide only those revisions whose hashes are passed or should we consider revisions numbers also. Differential Revision: https://phab.mercurial-scm.org/D1733

repoview: add a new filtername for accessing hidden commits This patch adds a new filter 'visible-hidden' for repository and will be used to return a repo object with user passed revisions unhidden. Unlike the directaccess extension in fb-hgext and previous series adding the functionality, this time we introduce only one new filter as whether to warn user or not is handled by scmutil.unhidehashlikerevs(). Differential Revision: https://phab.mercurial-scm.org/D1734

revsetlang: add utility function to return hash like symbols from the tree Functionalities like unhiding changesets whose rev/hash is passed by the user required the knowledge of rev/hashes in the user provided specs. This patch adds functions which can parse tree object and return a list of such values. Differential Revision: https://phab.mercurial-scm.org/D1732

repoview: add visibilityexception argument to filterrevs() and related fns After this patch, filterrevs() can take an optional argument visibilityexceptions which is a set of revs which should be exception to being hidden. The visibilityexceptions will be passed to the function computing hidden revisions for that filtername and are considered there while calculating the set of hidden revs. Differential Revision: https://phab.mercurial-scm.org/D1747