GetCollisionCheckPts fails on a single-waypoint trajectory

[mkoval]

ERROR: test_PlanToConfiguration_AlreadyAtGoal_FindsSolution (tests.planning.test_SnapPlanner.SnapPlannerTest)
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Traceback (most recent call last):
  File "/homes/mkoval/herb-ws/src/prpy/tests/planning/methods/PlanToConfiguration.py", line 72, in test_PlanToConfiguration_AlreadyAtGoal_FindsSolution
    self.PlanFromStartToGoalConfiguration(self.waypoint1, self.waypoint1)
  File "/homes/mkoval/herb-ws/src/prpy/tests/planning/methods/PlanToConfiguration.py", line 53, in PlanFromStartToGoalConfiguration
    path = self.planner.PlanToConfiguration(self.robot, config_goal)
  File "/homes/mkoval/herb-ws/src/prpy/src/prpy/planning/base.py", line 153, in __call__
    return call_planner()
  File "/homes/mkoval/herb-ws/src/prpy/src/prpy/planning/base.py", line 133, in call_planner
    *args, **kw_args)
  File "/homes/mkoval/herb-ws/src/prpy/src/prpy/planning/snap.py", line 67, in PlanToConfiguration
    return self._Snap(robot, goal, **kw_args)
  File "/homes/mkoval/herb-ws/src/prpy/src/prpy/planning/snap.py", line 141, in _Snap
    for _, q in GetCollisionCheckPts(robot, traj):
  File "/homes/mkoval/herb-ws/src/prpy/src/prpy/util.py", line 895, in GetCollisionCheckPts
    first_step, duration - start_time))
ValueError: First step 0.000000 is out of range (0, 0.000000]