fix issue in BulletClient (pybullet_utils.bullet_client) that may disconnect multiple times, causing issues when repeatedly creating a gym env

bump up pybullet to version 2.5.7

examples/pybullet/gym/pybullet_utils/bullet_client.py

@@ -21,7 +21,6 @@ class BulletClient(object):
         `pybullet.SHARED_MEMORY` connects to an existing simulation.
     """
     self._shapes = {}
-
     if connection_mode is None:
       self._client = pybullet.connect(pybullet.SHARED_MEMORY)
       if self._client >= 0:
@@ -32,14 +31,17 @@ class BulletClient(object):
 
   def __del__(self):
     """Clean up connection if not already done."""
-    try:
+    if self._client>=0:
-      pybullet.disconnect(physicsClientId=self._client)
+      try:
-    except pybullet.error:
+        pybullet.disconnect(physicsClientId=self._client)
-      pass
+        self._client = -1
+      except pybullet.error:
+        pass
 
   def __getattr__(self, name):
     """Inject the client id into Bullet functions."""
     attribute = getattr(pybullet, name)
+
     if inspect.isbuiltin(attribute):
       if name not in [
           "invertTransform",
@@ -51,4 +53,6 @@ class BulletClient(object):
           "getQuaternionFromEuler",
       ]:  # A temporary hack for now.
         attribute = functools.partial(attribute, physicsClientId=self._client)
+    if name=="disconnect":
+      self._client = -1 
     return attribute

setup.py

@@ -491,7 +491,7 @@ if 'BT_USE_EGL' in EGL_CXX_FLAGS:
 
 setup(
     name='pybullet',
-    version='2.5.6',
+    version='2.5.7',
     description=
     'Official Python Interface for the Bullet Physics SDK specialized for Robotics Simulation and Reinforcement Learning',
     long_description=