headsummary: expose the 'discardedheads' set in the headssummary That information will be useful to detect push race on related part of the history. See next changeset for details.

checkheads: perform obsolescence post processing directly in _headssummary The goal is to have the function directly return something meaningful and useful for the whole pull. Note: we skip adding post-processing in '_oldheadssummary' because if a client is too old for branchmap it will be too old for obsolescence too.

headssummary: directly feed the function with the 'pushop' object Our goal is to be able to perform the post processing directly into the '_headssummary' function. However before this patch the '_headsummary' function only had access to repo, remote, outgoing while the '_postprocessobsolete' function takes a 'pushop' object. Experience shows that having the 'pushop' object helps extensions so we update '_headssummary' to take a pushop object as argument.

checkheads: gather the postprocessing with other obsolescence specific code We extract this function from the loop and gather it with the rest of the obsolescence specific code. That will help to clarify the move of the whole logic inside the "heads summary" computation.

run-tests: add a way to list tests, with JSON and XUnit support Some test runners are interested in listing tests, so they can do their own filtering on top (usually based on attributes like historically observed runtime). Add support for that.

run-tests: install hg after computing tests to run We're going to add a way to list tests, and we don't need to install hg for that.

run-tests: make time field optional for xunit report We're going to use XUnit to list tests, and we don't have a time field in that case.

run-tests: factor out json write code into another method We're going to use this code to output a JSON-formatted listing of tests.

run-tests: factor out xunit write code into another method We're going to use this code to output an XUnit-formatted listing of tests.

revset: lookup descendents for negative arguments to ancestor operator Negative offsets to the `~` operator now search for descendents. The search is aborted when a node has more than one child as we do not have a definition for 'nth child'. Optionally we can introduce such a notion and take the nth child ordered by rev number. The current revset language does provides a short operator for ancestor lookup but not for descendents. This gives user a simple revset to move to the previous changeset, e.g. `hg up '.~1'` but not to the 'next' changeset. With this change userse can now use `.~-1` as a shortcut to move to the next changeset. This fits better into allowing users to specify revisions via revsets and avoiding the need for special `hg next` and `hg prev` operations. The alternative to negative offsets is adding a new operator. We do not have many operators in ascii left that do not require bash escaping (',', '_', and '/' come to mind). If we decide that we should add a more convenient short operator such as ('/', e.g. './1') we can later add it and allow ascendents lookup via negative numbers.