evolve: raise error.InterventionRequired instead of Abort when conflicts error.InterventionRequired is a better error to raise in such cases. Thanks to marmoute for noticing this.

changelog: add a changelog entry about divergence resolution We made a lots of progress there.

evolve: create resolved cset on successors of current parents While resolving content-divergence, sometimes, the parent can be obsolete and have a successor. We should consider the successors of the parents instead of obsolete parents as that will do something like orphan+content-divergence resolution both at the same time which is powerful and results in a single stack while resolving content-divergence of stacks. The test changes demonstrates that we can now successfully evolve a content divergent stack.

tests: fix a test case to not create conflicts This is the test case where we are testing about divergence resolution of stack of patches. If the stack is as follows: C1 C2 | | B1 B2 | | A1 A2 \/ base And A1-A2, B1-B2 and C1-C2 are content-divergent, and merging A1-A2 results in conflicts. Now if you resolve conflicts and continue resoling B1-B2, the conflicts of A1-A2 will still be there. We need somehow to understand the work we has done and not create conflicts again. To test the evolution functionality for now, we make sure conflicts does not occur.

evolve: introduce a resolutionparent variable and store it in evolvestate This patch introduces a resolutionparent variable which will be the parent of final changeset after resolving content-divergent changesets. Till now, the parent is always the parent of one of the divergent node, but now in upcoming cases, it can be a successor of both the parents of divergent nodes.

evolve: introduce a dirstatedance() fn to fix dirstate after parent change This patch introduces a dirstatedance() function which will be used after fixing the dirstate when we change parents using repo.dirstate.setparents(). Look at docs added for more details.

evolve: create a new commit instead of amending one of the divergents This patch changes the behavior of evolve command while resolving content-divergence to create a new commit instead of amending one of the divergent ones. In past, I have made this change, backed out this change and now today again I am doing this change, so let's dive in some history. Using cmdrewrite.amend() was never a good option as that requires hack to delete the evolvestate and also gives us less control over things. We can't make the commit on top of different parents as that of content-divergent ones. Due to all these, I first made this change to create a new commit instead of amending one. But, after few days, there was flakiness observed in the tests and turned out that we need to do some dirstate dance as repo.dirstate.setparents() does not always fix the dirstate. That flakiness was a blocker for progress at that time and we decided to switch to amend back so that we can have things working with some hacks and we can later fix the implementation part. Now, yesterday while tackling resolving content-divergence of a stack which is as follows: C1 C2 | | B1 B2 | | A1 A2 \/ base where, A1-A2, B1-B2, C1-C2 are content-divergent with each other. Now we can resolve A1-A2 very well because they have the same parent and let's say that resolution leads to A3. Now, we want to resolve B1-B2 and make the new resolution commit on top of A3 so that we can end up something like: C3 | B3 | A3 | base however, amending one of the divergent changesets, it's not possible to create a commit on a different parent like A3 here without some relocation. We should prevent relocation as that may leads to some conflicts and should change the parent before committing. So, looking ahead, we can't move with using amend as still using that we will need some relocation hacks making code ugly and prone to bad behaviors, bugs. Let's change back to creating a new commit so that we can move forward in a good way. About repo.dirstate.setparents() not setting the dirstate, I have researched yesterday night about how we can do that and found out that we can use cmdrewrite._uncommitdirstate() here. Expect upcoming patches to improve the documentation of that function. There are lot of test changes because of change in hash but there is no behavior change. The only behavior change is in test-evolve-abort-contentdiv.t which is nice because creating a new commit helps us in stripping that while aborting. We have a lot of testing of content-divergence and no behavior change gives enough confidence for making this change. I reviewed the patch carefully to make sure there is no behavior change and I suggest reviewer to do the same.

evolve: always order the revs to be evolved The current code only order the revs if we are resolving orphans and not in other case. The ordering is important when we pass --all and tackle multiple occurence of the same instability. Let's order the revs for each instability. There are enough test coverage of phase-divergence and content-divergence that I feel confident doing it because none of the test changed. The change in test-evolve-content-divergent.t demonstrates the indeed ordering helped.

tests: add test of resolution of content-divergent stacks This patch adds a test of resolution of content-divergence stacks where a series of changesets get mutated as two different series resulting in whole content-divergent stacks. As the tests shows, we are not processing the changesets in right order which needs to be fixed first.

evolve: improve error messages when conflicts occur This patch improves the error messages when conflicts occur. First, we drop the line 'evolution failed', that is not the best line we can show and evolution didn't failed, it's just interrupted by the conflicts and when user will run `hg evolve --continue`, things will be fine. I still remember when I first saw 'evolution failed', I got a bit scare as am I in a recoverable position or not. So let's drop this scary line. Second, we replace the error messages to say `resolve conflicts and see help-topic`. The help topic was added recently and documents all the three flags very well. Addition of tests also showed that all the three flags works fine with all the three instability type. So we should advertise them more. Third, we now raise the error with our error message rather than raising MergeFailure and having evolution related text in hint or stderr above. This increase the focus on the error message we want to show. After this patch, I think error messages by evolve in case of conflicts will be same in every case.