narrow: drop support for remote expansion (BC) Previous patches to validate narrow patterns accidentically dropped support for the include: syntax that allows patterns to be expanded from a remote. This feature was never implemented in core and is only implemented on Google's custom server. Per @martinvonz's review comment in D4522, it is OK to drop this feature since it isn't used. The concept of this feature does seem useful. I anticipate it making a comeback some day in some shape or form. But for now, let's jettison the dead code. Differential Revision: https://phab.mercurial-scm.org/D4530