Fix code style issue

Author: sdementen

lib/matplotlib/backend_bases.py

@@ -3044,8 +3044,8 @@ def release_zoom(self, event):
             # ignore singular clicks - 5 pixels is a threshold
             # allows the user to "cancel" a zoom action
             # by zooming by less than 5 pixels
-            if (abs(x - lastx) < 5 and self._zoom_mode!="y") \
-                    or (abs(y - lasty) < 5 and self._zoom_mode!="x"):
+            if ((abs(x - lastx) < 5 and self._zoom_mode!="y") or
+                (abs(y - lasty) < 5 and self._zoom_mode!="x")):
                 self._xypress = None
                 self.release(event)
                 self.draw()