change except syntax

Author: zhoujd

config/default

@@ -14,7 +14,7 @@ if not os.path.exists(assets):
   try:
     with tarfile.open("{}.tbz2".format(assets), "r:*") as tf:
       tf.extractall(media.mypath)
-  except tarfile.ReadError, e:
+  except tarfile.ReadError as e:
     assert 0, ("Failed to extract assets.  Did you forget to"
       " initialize git lfs (see README.md)?")
 

lib/metrics.py

@@ -85,7 +85,7 @@ def __exit__(self, type, value, tb):
   def next_frame(self):
     try:
       return self.reader(self.fd, self.width, self.height)
-    except Exception, e:
+    except Exception as e:
       e.args += tuple(["frame {}/{}".format(self.nreads, self.nframes)])
       raise
     finally: