convexsweeptest issue

[leethunchbck]

Hi,

i am using convexsweeptest for a kinematic controller and it fails on some instances.
the test sweeps a box shape (no rotation) against btBvhTriangleMeshShape,the problem
occurs only with a single triangle.instead of hitfraction ~.5 its returning nohits.

i included a test case,if i change the last vertex position by small amount the sweeptest returns .51 otherwise 1.0 (should return .51)

i am using r1975.debug build.