Gulp and bower++, could break stuff

static/app/bower_components/bootstrap/less/mixins/background-variant.less

@@ -0,0 +1,8 @@
+// Contextual backgrounds
+
+.bg-variant(@color) {
+  background-color: @color;
+  a&:hover {
+    background-color: darken(@color, 10%);
+  }
+}