Ensure legend_field takes precedence over legend_label

Author: philippjfr

holoviews/plotting/bokeh/element.py

@@ -1062,6 +1062,8 @@ def _init_glyph(self, plot, mapping, properties):
         if isinstance(plot_method, tuple):
             # Handle alternative plot method for flipped axes
             plot_method = plot_method[int(self.invert_axes)]
+        if 'legend_field' in properties and 'legend_label' in properties:
+            del properties['legend_label']
         renderer = getattr(plot, plot_method)(**dict(properties, **mapping))
         return renderer, renderer.glyph