do not coerce hoverlabel if it's undefined at trace level

Author: antoinerg

src/plots/plots.js

@@ -1171,10 +1171,12 @@ plots.supplyTraceDefaults = function(traceIn, traceOut, colorIndex, layout, trac
             traceOut._dfltShowLegend = false;
         }
 
-        Registry.getComponentMethod(
-            'fx',
-            'supplyDefaults'
-        )(traceIn, traceOut, defaultColor, layout);
+        if(_module && _module.attributes.hoverlabel !== undefined) {
+            Registry.getComponentMethod(
+                'fx',
+                'supplyDefaults'
+            )(traceIn, traceOut, defaultColor, layout);
+        }
 
         // TODO add per-base-plot-module trace defaults step
 

src/traces/parcoords/attributes.js

@@ -20,6 +20,8 @@ var templatedArray = require('../../plot_api/plot_template').templatedArray;
 module.exports = {
     domain: domainAttrs({name: 'parcoords', trace: true, editType: 'calc'}),
 
+    hoverlabel: undefined,
+
     labelfont: fontAttrs({
         editType: 'calc',
         description: 'Sets the font for the `dimension` labels.'