More accurate checking for overlapped ranges.

A RangeSet has half-closed half-open bounds. For example, "3,5" contains
blocks 3 and 4. So "3,5" and "5,7" are actually not overlapped.

Bug: 22098085
Change-Id: I362d259f8b5d62478858ad0422b635bc5068698d
(cherry picked from commit c0f56ad7)