Set packet_ends = None before using in dviread.py

cclauss · web-flow · commit 11005929ecce · 2018-02-14T10:28:12.000+01:00
__packed_ends__ is used on lines 649 and 653 but it is not defined/set until line 666.  This drives linters nuts because it is safer to set variables before using them.
diff --git a/lib/matplotlib/dviread.py b/lib/matplotlib/dviread.py
@@ -640,7 +640,7 @@ def _read(self):
         Read one page from the file. Return True if successful,
         False if there were no more pages.
         """
-        packet_len, packet_char, packet_width = None, None, None
+        packet_char, packet_ends, packet_len, packet_width = None, None, None, None
         while True:
             byte = ord(self.file.read(1)[0])
             # If we are in a packet, execute the dvi instructions
