make sure function input to breaks work with manual scale

Author: thomasp85

R/scale-manual.r

@@ -132,7 +132,7 @@ manual_scale <- function(aesthetic, values = NULL, breaks = waiver(), ...) {
 
   # order values according to breaks
   if (is.vector(values) && is.null(names(values)) && !is.waive(breaks) &&
-      !is.null(breaks)) {
+      !is.null(breaks) && !is.function(breaks)) {
     if (length(breaks) <= length(values)) {
       names(values) <- breaks
     } else {