transaction: document `tr.add`

transaction: drop backupentries logic from startgroup and endgroup The `startgroup` and `endgroup` methods are used in a very specific context to wrap a very specific operation (revlog truncation). It does not make sense to perform any other operations during such a "group" (eg:file backup). There is currently no user of backupfile during a "group" so we drop the group-specific code and restrict authorized operations during "group".

transaction: document startgroup and endgroup These enigmatic methods are only used in repair. We document them to clarify there purpose and user.

transaction: mark backup-related attributes private As the transaction is gaining more functions and attributes, it is important to clarify what is part of the public API.

transaction: document the contents of `tr.backupentries` Now that all items are known we can document it.

transaction: drop the third item in `tr.backupentries` This third item is always None and never used.

rebase: fix rebase with no common ancestors (issue4446) The new rebase revset didn't check for the case when there are no common ancestors. Now it does. The new behavior should be the same as the pre-3.2 behavior. Added a test.

test-run-tests: accept more levels of precision and trailing ws (issue4440) simplejson produces slightly different output from the built-in json module, specifically: * It uses 0.000 instead of 0.0000 * It likes to put a trailing space after a comma This change works around both of those variations.

merge with stable

changegroup.cg2packer: lookup 'group' via inheritance chain This lets extensions insert themselves in the class hierarchy.

context.status: only filter suspect symlinks in the dirstate status We don't care about filtering out symlinks that have already been committed with full content, only those that have been accidentally resolved in the working directory.

context.status: inline _poststatus() By inlining _poststatus() into _buildstatus(), it becomes clearer that it is only called for the workingctx.

context.status: remove now-empty _prestatus()

context.status: call _dirstatestatus() from within _buildstatus() By making the call to _dirstatestatus() within _buildstatus(), it becomes clearer that it's called only for the workingctx.

context.status: move manifest caching trick to _buildstatus() In basectx._buildstatus(), we read the manifests for the two revisions being compared. For "caching reasons" unknown to me, it is better to read the earlier manifest first, which basectx._prestatus() takes care of. However, if the 'self' context is a committablectx and the 'other' context is the parent of the working directory (as in the very common case of plain "hg status"), there is no need to read any manifests at all -- all that's needed is the dirstate status. To avoid reading the manifests, _prestatus() is overridden in committablectx and avoids calling its super method, and _buildstatus() calls its super method only if the 'other' context is not the parent of the working directory. It seems easier to follow what's happening if we move the pre-fetching to _buildstatus() just before the place where the manifests are fetched. We just need to add an extra check that the revision is not None to handle the case that was previously handled by subclass overriding. That also makes it safe for committablectx._prestatus() to call its parent, although the latter now becomes empty, so we won't bother.

context.status: remove unused arguments from _matchstatus()