Previous matplotlib had a bug. As per documentation, specifying empty

string for sym argument should prevent drawing fliers for boxplots.

As an example, the following script displays fliers in the boxplot
when it shouldn't.

    import matplotlib.pyplot as plt

    data = list(range(0,100)) + [200,-200,250,-250]
    bp = plt.boxplot(data,sym='',widths=.3)
    plt.show()

Added logic to ensure empty sym string does not display fliers.

Author: bmistree

lib/matplotlib/axes/_axes.py

@@ -3081,6 +3081,10 @@ def boxplot(self, x, notch=False, sym=None, vert=True, whis=1.5,
                     flierprops['markeredgecolor'] = color
                     flierprops['markerfacecolor'] = color
 
+        # do not show fliers if sym is empty string
+        if sym == '':
+            showfliers = False
+
         # replace medians if necessary:
         if usermedians is not None:
             if (len(np.ravel(usermedians)) != len(bxpstats) or