These 2 rectangles used to intersect fine:
0 0 50 50 / 50 0
0 0 50 50 / 0 50
But the computed result was:
0 0 50 50 / 50
which is not a valid rectangle, because the corners overlap.
Make sure such rectangles return NOT_REPRESENTABLE.
The above rectangle has been added to the testsuite.
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