title: stat_summary() and fun.data = mean_sdl not working
body: <pre><code>set.seed(1) # generate random data
  day1 = rnorm(20,0,1)
  day2 = rnorm(20,5,1)
  Subject &lt;- rep(paste0('S',seq(1:20)), 2)
  Data &lt;- data.frame(Value = matrix(c(day1,day2),ncol=1))
  Day &lt;- rep(c('Day 1', 'Day 2'), each = length(day1))
  df &lt;- cbind(Subject, Data, Day)
  </code></pre>
  <p>Using this random data, I'd like to plot individual points with unique color for each subject and a summary point (mean + standard deviation).</p>
  <p>It seems that the plot is okay when all points are plotted with the same color because <code>stat_summary(fun.data = mean_sdl)</code> works properly.</p>
  <pre><code>ggplot(data = df, mapping = aes(x= Day, y =Value)) +
    stat_summary(fun.data = mean_sdl, fun.args = list(mult = 2),
                 geom = 'pointrange', fatten = 3*1.2, size = 1.2,
                 color= 'black')  +
    geom_point(size = 2) 
  </code></pre>
  <p><a href="https://i.stack.imgur.com/PxlC9.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/PxlC9.png" alt="enter image description here" /></a>
  But not when all points have unique color (for each subject).</p>
  <pre><code>ggplot(data = df, mapping = aes(x = Day, y = Value,
                                  fill = Subject)) +
    stat_summary(fun.data = mean_sdl, fun.args = list(mult = 2),
                 geom = 'pointrange', fatten = 3*1.2, size = 1.2,
                 color = 'black') +
    geom_point(shape = 21, color = 'white', size = 2) 
  </code></pre>
  <p><a href="https://i.stack.imgur.com/KMhRF.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KMhRF.png" alt="enter image description here" /></a></p>