prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  exception views squash the original exception if an exception view predicate is tested and fails
  If you register an exception view with a predicate such as `config.add_view(view, context=Exception, request_method='GET')`, this will cause any errors from a POST request (without a matching exception view) to be squashed into a `PredicateMismatch` exception which will be propagated up the wsgi stack instead of the original exception.
  
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `pyramid/tweens.py`
  Content:
  ```
  1 import sys
  2 
  3 from pyramid.interfaces import (
  4     IExceptionViewClassifier,
  5     IRequest,
  6     )
  7 
  8 from zope.interface import providedBy
  9 from pyramid.view import _call_view
  10 
  11 def excview_tween_factory(handler, registry):
  12     """ A :term:`tween` factory which produces a tween that catches an
  13     exception raised by downstream tweens (or the main Pyramid request
  14     handler) and, if possible, converts it into a Response using an
  15     :term:`exception view`."""
  16 
  17     def excview_tween(request):
  18         attrs = request.__dict__
  19         try:
  20             response = handler(request)
  21         except Exception as exc:
  22             # WARNING: do not assign the result of sys.exc_info() to a local
  23             # var here, doing so will cause a leak.  We used to actually
  24             # explicitly delete both "exception" and "exc_info" from ``attrs``
  25             # in a ``finally:`` clause below, but now we do not because these
  26             # attributes are useful to upstream tweens.  This actually still
  27             # apparently causes a reference cycle, but it is broken
  28             # successfully by the garbage collector (see
  29             # https://github.com/Pylons/pyramid/issues/1223).
  30             attrs['exc_info'] = sys.exc_info()
  31             attrs['exception'] = exc
  32             # clear old generated request.response, if any; it may
  33             # have been mutated by the view, and its state is not
  34             # sane (e.g. caching headers)
  35             if 'response' in attrs:
  36                 del attrs['response']
  37             # we use .get instead of .__getitem__ below due to
  38             # https://github.com/Pylons/pyramid/issues/700
  39             request_iface = attrs.get('request_iface', IRequest)
  40             provides = providedBy(exc)
  41             response = _call_view(
  42                 registry,
  43                 request,
  44                 exc,
  45                 provides,
  46                 '',
  47                 view_classifier=IExceptionViewClassifier,
  48                 request_iface=request_iface.combined
  49                 )
  50             if response is None:
  51                 raise
  52 
  53         return response
  54 
  55     return excview_tween
  56 
  57 MAIN = 'MAIN'
  58 INGRESS = 'INGRESS'
  59 EXCVIEW = 'pyramid.tweens.excview_tween_factory'
  60
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/pyramid/tweens.py b/pyramid/tweens.py
  --- a/pyramid/tweens.py
  +++ b/pyramid/tweens.py
  @@ -1,5 +1,7 @@
   import sys
   
  +from pyramid.compat import reraise
  +from pyramid.exceptions import PredicateMismatch
   from pyramid.interfaces import (
       IExceptionViewClassifier,
       IRequest,
  @@ -38,17 +40,26 @@
               # https://github.com/Pylons/pyramid/issues/700
               request_iface = attrs.get('request_iface', IRequest)
               provides = providedBy(exc)
  -            response = _call_view(
  -                registry,
  -                request,
  -                exc,
  -                provides,
  -                '',
  -                view_classifier=IExceptionViewClassifier,
  -                request_iface=request_iface.combined
  -                )
  +            try:
  +                response = _call_view(
  +                    registry,
  +                    request,
  +                    exc,
  +                    provides,
  +                    '',
  +                    view_classifier=IExceptionViewClassifier,
  +                    request_iface=request_iface.combined
  +                    )
  +
  +            # if views matched but did not pass predicates, squash the error
  +            # and re-raise the original exception
  +            except PredicateMismatch:
  +                response = None
  +
  +            # re-raise the original exception as no exception views were
  +            # able to handle the error
               if response is None:
  -                raise
  +                reraise(*attrs['exc_info'])
   
           return response
  
verification_info: {"golden_diff": "diff --git a/pyramid/tweens.py b/pyramid/tweens.py\n--- a/pyramid/tweens.py\n+++ b/pyramid/tweens.py\n@@ -1,5 +1,7 @@\n import sys\n \n+from pyramid.compat import reraise\n+from pyramid.exceptions import PredicateMismatch\n from pyramid.interfaces import (\n     IExceptionViewClassifier,\n     IRequest,\n@@ -38,17 +40,26 @@\n             # https://github.com/Pylons/pyramid/issues/700\n             request_iface = attrs.get('request_iface', IRequest)\n             provides = providedBy(exc)\n-            response = _call_view(\n-                registry,\n-                request,\n-                exc,\n-                provides,\n-                '',\n-                view_classifier=IExceptionViewClassifier,\n-                request_iface=request_iface.combined\n-                )\n+            try:\n+                response = _call_view(\n+                    registry,\n+                    request,\n+                    exc,\n+                    provides,\n+                    '',\n+                    view_classifier=IExceptionViewClassifier,\n+                    request_iface=request_iface.combined\n+                    )\n+\n+            # if views matched but did not pass predicates, squash the error\n+            # and re-raise the original exception\n+            except PredicateMismatch:\n+                response = None\n+\n+            # re-raise the original exception as no exception views were\n+            # able to handle the error\n             if response is None:\n-                raise\n+                reraise(*attrs['exc_info'])\n \n         return response\n", "issue": "exception views squash the original exception if an exception view predicate is tested and fails\nIf you register an exception view with a predicate such as `config.add_view(view, context=Exception, request_method='GET')`, this will cause any errors from a POST request (without a matching exception view) to be squashed into a `PredicateMismatch` exception which will be propagated up the wsgi stack instead of the original exception.\n\n", "before_files": [{"content": "import sys\n\nfrom pyramid.interfaces import (\n    IExceptionViewClassifier,\n    IRequest,\n    )\n\nfrom zope.interface import providedBy\nfrom pyramid.view import _call_view\n\ndef excview_tween_factory(handler, registry):\n    \"\"\" A :term:`tween` factory which produces a tween that catches an\n    exception raised by downstream tweens (or the main Pyramid request\n    handler) and, if possible, converts it into a Response using an\n    :term:`exception view`.\"\"\"\n\n    def excview_tween(request):\n        attrs = request.__dict__\n        try:\n            response = handler(request)\n        except Exception as exc:\n            # WARNING: do not assign the result of sys.exc_info() to a local\n            # var here, doing so will cause a leak.  We used to actually\n            # explicitly delete both \"exception\" and \"exc_info\" from ``attrs``\n            # in a ``finally:`` clause below, but now we do not because these\n            # attributes are useful to upstream tweens.  This actually still\n            # apparently causes a reference cycle, but it is broken\n            # successfully by the garbage collector (see\n            # https://github.com/Pylons/pyramid/issues/1223).\n            attrs['exc_info'] = sys.exc_info()\n            attrs['exception'] = exc\n            # clear old generated request.response, if any; it may\n            # have been mutated by the view, and its state is not\n            # sane (e.g. caching headers)\n            if 'response' in attrs:\n                del attrs['response']\n            # we use .get instead of .__getitem__ below due to\n            # https://github.com/Pylons/pyramid/issues/700\n            request_iface = attrs.get('request_iface', IRequest)\n            provides = providedBy(exc)\n            response = _call_view(\n                registry,\n                request,\n                exc,\n                provides,\n                '',\n                view_classifier=IExceptionViewClassifier,\n                request_iface=request_iface.combined\n                )\n            if response is None:\n                raise\n\n        return response\n\n    return excview_tween\n\nMAIN = 'MAIN'\nINGRESS = 'INGRESS'\nEXCVIEW = 'pyramid.tweens.excview_tween_factory'\n", "path": "pyramid/tweens.py"}], "after_files": [{"content": "import sys\n\nfrom pyramid.compat import reraise\nfrom pyramid.exceptions import PredicateMismatch\nfrom pyramid.interfaces import (\n    IExceptionViewClassifier,\n    IRequest,\n    )\n\nfrom zope.interface import providedBy\nfrom pyramid.view import _call_view\n\ndef excview_tween_factory(handler, registry):\n    \"\"\" A :term:`tween` factory which produces a tween that catches an\n    exception raised by downstream tweens (or the main Pyramid request\n    handler) and, if possible, converts it into a Response using an\n    :term:`exception view`.\"\"\"\n\n    def excview_tween(request):\n        attrs = request.__dict__\n        try:\n            response = handler(request)\n        except Exception as exc:\n            # WARNING: do not assign the result of sys.exc_info() to a local\n            # var here, doing so will cause a leak.  We used to actually\n            # explicitly delete both \"exception\" and \"exc_info\" from ``attrs``\n            # in a ``finally:`` clause below, but now we do not because these\n            # attributes are useful to upstream tweens.  This actually still\n            # apparently causes a reference cycle, but it is broken\n            # successfully by the garbage collector (see\n            # https://github.com/Pylons/pyramid/issues/1223).\n            attrs['exc_info'] = sys.exc_info()\n            attrs['exception'] = exc\n            # clear old generated request.response, if any; it may\n            # have been mutated by the view, and its state is not\n            # sane (e.g. caching headers)\n            if 'response' in attrs:\n                del attrs['response']\n            # we use .get instead of .__getitem__ below due to\n            # https://github.com/Pylons/pyramid/issues/700\n            request_iface = attrs.get('request_iface', IRequest)\n            provides = providedBy(exc)\n            try:\n                response = _call_view(\n                    registry,\n                    request,\n                    exc,\n                    provides,\n                    '',\n                    view_classifier=IExceptionViewClassifier,\n                    request_iface=request_iface.combined\n                    )\n\n            # if views matched but did not pass predicates, squash the error\n            # and re-raise the original exception\n            except PredicateMismatch:\n                response = None\n\n            # re-raise the original exception as no exception views were\n            # able to handle the error\n            if response is None:\n                reraise(*attrs['exc_info'])\n\n        return response\n\n    return excview_tween\n\nMAIN = 'MAIN'\nINGRESS = 'INGRESS'\nEXCVIEW = 'pyramid.tweens.excview_tween_factory'\n", "path": "pyramid/tweens.py"}]}