rebase: add the --inmemory option flag; assign a wctx object for the rebase...
rebase: add the --inmemory option flag; assign a wctx object for the rebase
In the future, the --inmemory flag might be deprecated in favor of something more
intelligent (for example, always rebasing in-memory if the working copy parent
isn't in the rebaseset). But we might keep it as a way to explicitly force IMM
on or off.
Differential Revision:
https://phab.mercurial-scm.org/D1232