more general solution - make sure 'colors' is a list rather than an array

Author: alimuldal

lib/matplotlib/axes/_axes.py

@@ -1180,11 +1180,8 @@ def eventplot(self, positions, orientation='horizontal', lineoffsets=1,
         if len(linewidths) == 1:
             linewidths = np.tile(linewidths, len(positions))
         if len(colors) == 1:
-            if colors[0] is None:
-                colors = colors * len(positions)
-            else:
-                colors = np.asanyarray(colors)
-                colors = np.tile(colors, [len(positions), 1])
+            colors = list(colors)
+            colors = colors * len(positions)
         if len(linestyles) == 1:
             linestyles = [linestyles] * len(positions)