ERROR: Macro Image(,) failed: IndexError: pop from empty list

[Ryan J Ollos]

2017-03-26 19:02:18,394 Trac[formatter] ERROR: Macro Image(,) failed:
Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/trac/wiki/formatter.py", line 793, in _macro_formatter
    return macro.ensure_inline(macro.process(args))
  File "build/bdist.linux-x86_64/egg/trac/wiki/formatter.py", line 362, in process
    text = self.processor(text)
  File "build/bdist.linux-x86_64/egg/trac/wiki/formatter.py", line 349, in _macro_processor
    text)
  File "build/bdist.linux-x86_64/egg/trac/wiki/macros.py", line 539, in expand_macro
    filespec = args.pop(0)
IndexError: pop from empty list

Proposed fix:

trac/wiki/macros.py

@@ -538 +538 @@
     _quoted_re = re.compile("(?:[\"'])(.*)(?:[\"'])$")
 
     def expand_macro(self, formatter, name, content):
+        args = None
         if content:
             content = stripws(content)
-        if not content:
+            # parse arguments
+            # we expect the 1st argument to be a filename (filespec)
+            args = [stripws(arg) for arg
+                                 in self._split_args_re.split(content)[1::2]]
+        if not args:
             return ''
-        # parse arguments
-        # we expect the 1st argument to be a filename (filespec)
-        args = [stripws(arg) for arg
-                             in self._split_args_re.split(content)[1::2]]
         # strip unicode white-spaces and ZWSPs are copied from attachments
         # section (#10668)
         filespec = args.pop(0)