getCategoryIndex falls back to the former implementation to fix the failed unit test case

Author: hy9be

src/plots/cartesian/set_convert.js

@@ -148,8 +148,13 @@ module.exports = function setConvert(ax, fullLayout) {
         // d2l/d2c variant that that won't add categories but will also
         // allow numbers to be mapped to the linearized axis positions
         var index;
-        if(ax._categoriesMap) { index = ax._categoriesMap[v] ? ax._categoriesMap : undefined; }
-        if(index !== undefined) { return index; }
+        if(ax._categoriesMap) {
+            index = ax._categoriesMap[v] ? ax._categoriesMap : undefined;
+            if(index !== undefined) return index;
+        } else {
+            index = ax._categories.indexOf(v);
+            if(index !== -1) return index;
+        }
         if(typeof v === 'number') { return v; }
     }