Fix quadratic behavior of PyPy's deque.remove() method

diff --git a/lib_pypy/_collections.py b/lib_pypy/_collections.py
--- a/lib_pypy/_collections.py
+++ b/lib_pypy/_collections.py
@@ -142,12 +142,18 @@
         return c

     def remove(self, value):
-        # Need to be defensive for mutating comparisons
-        for i in range(len(self)):
-            if self[i] == value:
-                del self[i]
-                return
-        raise ValueError("deque.remove(x): x not in deque")
+        # Need to defend against mutating or failing comparisons
+        i = 0
+        try:
+            for i in range(len(self)):
+                if self[0] == value:
+                    self.popleft()
+                    return
+                self.append(self.popleft())
+            i += 1
+            raise ValueError("deque.remove(x): x not in deque")
+        finally:
+            self.rotate(i)

     def rotate(self, n=1):
         length = len(self)