auto-scale the max value of y when njobs > 1 (#1648)

Author: aloctavodia

pymc3/plots.py

@@ -104,7 +104,7 @@ def traceplot(trace, varnames=None, transform=lambda x: x, figsize=None,
                                      lw=1.5, alpha=alpha)
                 except KeyError:
                     pass
-
+        ax[i, 0].set_ylim(ymin=0)
     plt.tight_layout()
     return ax
 
@@ -132,8 +132,6 @@ def kdeplot_op(ax, data, prior=None, prior_alpha=1, prior_style='--'):
 
         ax.plot(x, density)
 
-    ax.set_ylim(ymin=0)
-
 
 def make_2d(a):
     """Ravel the dimensions after the first.