fixes in GJK/btGjkEpa2, thanks to Dev0 for reporting and Nathanael for fixing

src/BulletCollision/NarrowPhaseCollision/btGjkEpa2.cpp

@@ -287,7 +287,7 @@ bool					EncloseOrigin()
 				{
 				btVector3		axis=btVector3(0,0,0);
 				axis[i]=1;
-				if(btFabs(dot(axis,d))>0)
+				if(btFabs(dot(axis,d))<1)
 					{
 					const btVector3	p=cross(d,axis);
 					appendvertice(*m_simplex, p);

src/BulletCollision/NarrowPhaseCollision/btGjkPairDetector.cpp

@@ -144,6 +144,13 @@ void btGjkPairDetector::getClosestPoints(const ClosestPointInput& input,Result&
 				break;
 			}
 
+			if(m_cachedSeparatingAxis.length2()<REL_ERROR2)
+            {
+                m_degenerateSimplex = 6;
+                checkSimplex = true;
+                break;
+            }
+
 			btScalar previousSquaredDistance = squaredDistance;
 			squaredDistance = m_cachedSeparatingAxis.length2();