The GR-CHANGE-VIEW element responds to changes in "Patch Set" select
input by constructing and loading a new router URL. However, if the base
patch did not have PARENT selected, it would not be included in the new
route, effectively resetting the base patch to PARENT whenever the patch
is changed.
With this change, the base patch selection is included in such router
URLs.
Bug: Issue 5254
Change-Id: I757bba23f6e23d4b63bc57183c65d2365cb88f5f