view CONTRIBUTING @ 33284:b2670290eab4

followlines: join merge parents line ranges in blockdescendants() (issue5595)

In blockdescendants(), we had an assertion when line range of a merge
changeset was not consistent depending on which parent was considered for
computation. For instance, this might occur when file content (in lookup
range) is significantly different between parent branches of the merge as
demonstrated in added tests (where we almost completely rewrite the "baz" file
while also introducing similarities with its content in the other branch we
later merge to).

Now, in such case, we combine line ranges from all parents by storing the
envelope of both line ranges. This is conservative (the line range is
extended, possibly unnecessarily) but at least this should avoid missing
descendants with changes in a range that would fall in that of one parent but
not in another one (the case of "baz: narrow change (2->2+)" changeset in
tests).

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