Workflow macro should trap exceptions when parsing content

[Ryan J Ollos]

The following content will raise a ParsingError:

 accept = new,accepted -> accepted
 accept.permissions = TICKET_MODIFY
accept.operations = set_owner_to_self

An error is found in the logs:

11:01:18 PM Trac[formatter] ERROR: Processor Workflow failed:
Traceback (most recent call last):
  File "/home/user/Workspace/t11944/teo-rjollos.git/trac/wiki/formatter.py", line 1181, in _exec_processor
    return processor.process(text)
  File "/home/user/Workspace/t11944/teo-rjollos.git/trac/wiki/formatter.py", line 358, in process
    text = self.processor(text)
  File "/home/user/Workspace/t11944/teo-rjollos.git/trac/wiki/formatter.py", line 342, in _macro_processor
    text, self.args)
  File "/home/user/Workspace/t11944/teo-rjollos.git/trac/ticket/default_workflow.py", line 479, in expand_macro
    parser.readfp(StringIO(text))
  File "/usr/lib/python2.7/ConfigParser.py", line 324, in readfp
    self._read(fp, filename)
  File "/usr/lib/python2.7/ConfigParser.py", line 546, in _read
    raise e
ParsingError: File contains parsing errors: <???>
	[line  2]: u' accept = new,accepted -> accepted\n'
ParsingError: File contains parsing errors: <???>
	[line  2]: u' accept = new,accepted -> accepted\n'
	[line  3]: u' accept.permissions = TICKET_MODIFY\n'

The following patch would fix the issue, but it would be nice to have the line breaks in the error message rendered.

trac/ticket/default_workflow.py

@@ -16 +16 @@
 #
 # Author: Eli Carter
 
-from ConfigParser import RawConfigParser
+from ConfigParser import ParsingError, RawConfigParser
 from StringIO import StringIO
 from collections import defaultdict
 from functools import partial
@@ -34 +34 @@
 from trac.util.presentation import separated
 from trac.util.translation import _, tag_, cleandoc_
 from trac.web.chrome import Chrome, add_script, add_script_data
+from trac.wiki.formatter import system_message
 from trac.wiki.macros import WikiMacroBase
 
 # -- Utilities for the ConfigurableTicketWorkflow
@@ -476 +477 @@
             if '[ticket-workflow]' not in text:
                 text = '[ticket-workflow]\n' + text
             parser = RawConfigParser()
-            parser.readfp(StringIO(text))
+            try:
+                parser.readfp(StringIO(text))
+            except ParsingError, e:
+                return system_message(_("Error parsing workflow."),
+                                      unicode(e))
             raw_actions = list(parser.items('ticket-workflow'))
         actions = parse_workflow_config(raw_actions)
         states = list(set(