evolve: add a test reflecting wrong behaviour of content-div resolution This patch shows that currently the case when stack of divergent csets have different parents is not handled correctly. For a stack of csets which has different parent, right behaviour is to relocate every node before performing merge but present implementation only relocate first cset in the stack and skip relocation for the rest of csets, this is not what we expect it to do. Next patch will be about fixing this issue.

compat: add support for new arg name in memfilectx.__init__ This makes us compatible with 550a172a603b (memctx: rename constructor argument "copied" to "copysource" (API), 2019-03-19).