Merge pull request matplotlib#3808 from tacaswell/colorbar_norm_bug

BUG : fix matplotlib#3805

Author: efiring

lib/matplotlib/colorbar.py

@@ -653,12 +653,14 @@ def _process_values(self, b=None):
             self._values = v
             return
         else:
-            self.norm.vmin, self.norm.vmax = mtrans.nonsingular(self.norm.vmin,
-                                                                self.norm.vmax,
-                                                                expander=0.1)
             if not self.norm.scaled():
                 self.norm.vmin = 0
                 self.norm.vmax = 1
+
+            self.norm.vmin, self.norm.vmax = mtrans.nonsingular(self.norm.vmin,
+                                                                self.norm.vmax,
+                                                                expander=0.1)
+
             b = self.norm.inverse(self._uniform_y(self.cmap.N + 1))
             if self._extend_lower():
                 b[0] = b[0] - 1

lib/matplotlib/tests/test_colorbar.py

@@ -246,6 +246,13 @@ def test_remove_from_figure_no_gridspec():
     _test_remove_from_figure(False)
 
 
+@cleanup
+def test_colorbarbase():
+    # smoke test from #3805
+    ax = plt.gca()
+    ColorbarBase(ax, plt.cm.bone)
+
+
 if __name__ == '__main__':
     import nose
     nose.runmodule(argv=['-s', '--with-doctest'], exit=False)