#20 expect_after matches instead of expect

[heinrichmartin]

Actual behavior of attached expect_after.exp:

GIVEN two spawn processes A and B
AND A has a matching expect_after pattern applied
WHEN expect is called with a matching pattern for B only
THEN the expect_after pattern matches for A

Expected behavior:
THEN the expect pattern matches for B

The attached expect_after.patch seems to resolve this issue (leaving all 29 test cases intact).