Bug: 2671465 quiver plot adds unwanted lines to image

svn path=/trunk/matplotlib/; revision=7207

Author: mdboom

lib/matplotlib/quiver.py

@@ -500,6 +500,10 @@ def _h_arrows(self, length):
         minsh = self.minshaft * self.headlength
         N = len(length)
         length = length.reshape(N, 1)
+        # This number is chosen based on when pixel values overflow in Agg
+        # causing rendering errors
+        length = np.minimum(length, 2 ** 16)
+
         # x, y: normal horizontal arrow
         x = np.array([0, -self.headaxislength,
                         -self.headlength, 0], np.float64)