revlog: in addgroup, reject ill-formed deltas based on censored nodes To ensure interoperability when clones disagree about which file nodes are censored, a restriction is made on deltas based on censored nodes. Any such delta must replace the full text of the base in a single patch. If the recipient of a delta considers the base to be censored and the delta is not in the expected form, the recipient must reject it, as it can't know if the source has also censored the base. For background and broader design of the censorship feature, see: http://mercurial.selenic.com/wiki/CensorPlan

mdiff: add helper for making deltas which replace the full text of a revision This helper will be used initially for censor-aware delta generation. Deltas which replace the full contents of the base revision are guaranteed to apply correctly regardless of whether the delta recipient has censored the base. For background and broader design of the censorship feature, see: http://mercurial.selenic.com/wiki/CensorPlan

revlog: add "iscensored()" to revlog public API The iscensored method will be used by the exchange layer to reject nonconforming deltas involving censored revisions (and to produce conforming deltas). For background and broader design of the censorship feature, see: http://mercurial.selenic.com/wiki/CensorPlan

filelog: allow censored files to contain padding data To ensure delta compatibility, when a revision is censored, it is padded to match the original data in size. The previous check does not allow for padding because it was added before padding was found to be a requirement. For more background and design of the censorship feature, see: mercurial.selenic.com/wiki/CensorPlan

revset: drop factory that promotes spanset to fullreposet All callers use fullreposet where appropriate. Backed out changeset fbae659543cf

revset: specify fullreposet without using spanset factory The factory function will be removed because the subsequent patches will make fullreposet(repo) not fully compatible with spanset(repo).

revset: make match function initiate query from full set by default This change is intended to avoid exposing the implementation detail to callers. I'm going to extend fullreposet to support "null" revision, so these mfunc calls will have to use fullreposet() instead of spanset().