template: add successors template Add a 'successorssets' template that returns the list of all closest known sucessorssets for a changectx. The elements of the list are changesets. The "closest successors" are the first locally known revisions encountered while, walking successors markers. It uses successorsets previously modified to support the closest argument. This logic respect repository filtering. So hidden revision will be skipped by this logic unless --hidden is specified. Since we only display the visible predecessors, this template will not display anything in most case. It makes a good candidate for inclusion in the default log output. I updated the test-obsmarker-template.t test file introduced with the predecessors template to test successorssets template.

template: add tests for more complex cases We add new tests for improving the coverage of existing obs-markers related template (predecessors) and the new one we are introducing (successorssets).

obsolete: closest divergent support Add a closest argument to successorssets changing the definition of latest successors. With "closest=false" (current behavior), latest successors are "leafs" on the obsmarker graph. They don't have any successor and are known locally. With "closest=true", latest successors are the closest locally-known changesets that are visible in the repository or repoview. Closest successors can be then obsolete, orphan. This will be used in a later patch to show the closest successor of changesets with the successorssets template.

obsolete: pass cache argument of successors set explicitly We plan to add a new argument to successorsets. But first we need to update all callers to pass cache argument explicitly to avoid arguments confusion.

obsolete: small doc update for 'successorssets' Clarify successorssets documentation before we start updating the main function. This patch serie will introduce the successorssets template, the opposite of predecessor templates. Successors will use successorssets function and requires some improvement so before doing that, we clean up successorssets a bit.

phabricator: do not read a same revision twice It's possible to set up non-linear dependencies in Phabricator like: o D4 |\ | o D3 | | o | D2 |/ o D1 The old `phabread` code will print D1 twice. This patch adds de-duplication to prevent that. Test Plan: Construct the above dependencies in a Phabricator test instance and make sure the old code prints D1 twice while the new code won't.

patch: make parsepatch optionally trim context lines Previously there is a suspicious `if False and delta > 0` which dates back to the beginning of hgext/record.py (b2607267236d). The "trimming context lines" feature could be useful (and is used by the next patch). So let's enable it. This patch adds a new `maxcontext` parameter to `recordhunk` and `parsepatch`, changing the `if False` condition to respect it. The old `trimcontext` implementation is also wrong - it does not update `toline` correctly and it does not do the right thing for `before` context. A doctest was added to guard us from making a similar mistake again. Since `maxcontext` is set to `None` (unlimited), there is no behavior change.

phabricator: try to fetch differential revisions in batch Previously, we read Differential Revisions one by one by calling `differential.query`. Fetching them one by one is suboptimal. Unfortunately, there is no Conduit API that allows us to get a stack of diffids using a single API call. This patch tries to be smarter using a simple heuristic: when fetching D59 as a stack, previous IDs like D51, D52, D53, ..., D58 are likely belonging to a same stack so just fetch them as well. Since `differential.query` only returns cheap metadata without expensive diff content, it shouldn't be a big problem for the server. Using a test Phabricator instance, this patch reduces `phabread` reading a 10 patch stack from about 13 to 30 seconds to 8 seconds.

phabricator: avoid calling differential.getcommitmessage Previously, we call differential.getcommitmessage API to get commit messages. Now we read that from "Differential Revision" object fetched via "differential.query" API. This removes one API call per patch.

phabricator: rework phabread to reduce memory usage and round-trips This patch reworked phabread a bit so it fetches the lightweight "Differential Revision" metadata for a stack first. Then read other data. This allows the code to: a) send 1 request to get all `hg:meta` data instead of N requests b) patches are read in desired order, no need to buffer the output "b)" reduces the memory usage from O(N^2) to O(N) since we no longer keep old patch contents in memory. The above `N` means the number of patches in the stack.