Use correct dist dir on beta

Author: brson

master/master.cfg

@@ -1154,7 +1154,7 @@ def distsnap_buildfactory(platform, channel_label):
 
     # Upload artifacts from slave
     slave_dist_dir = "dist"
-    if 'nightly' in channel_label or \
+    if 'nightly' in channel_label or 'beta' in channel_label or \
        'cross-host-linux' in platform or \
        'cross-rustbuild-linux' in platform:
         slave_dist_dir = "build/dist"