The attached diff fixes the following problem i'm seeing.  
Not sure whether it is correct or not, but at the very 
least it is a work around.

Templating Error
        exceptions.ValueError: Unknown spec <Date 
2004-07-27.00:00:0.000000>

Debugging information follows

While evaluating the standard:'context/history' expression 
on line 187 Current v
ariables:
templates <roundup.cgi.templating.Templates instance at 
0x3a8fa8>
repeat <roundup.cgi.PageTemplates.TALES.SafeMapping 
instance at 0x3aa0f8>
context <HTMLItem(0x3a8fd0) issue 246>
default <roundup.cgi.PageTemplates.TALES.Default 
instance at 0x3492b0>
db <roundup.cgi.templating.HTMLDatabase instance at 
0x3a8a80>
utils <roundup.cgi.templating.utils instance at 0x3a8f80>
request <roundup.cgi.templating.HTMLRequest instance 
at 0x6675d0>
tracker <module '_roundup_tracker_1' from 
'/u/roundup/systems/help/__init__.pyo'
>
template <Roundup PageTemplate 'issue.item.html'> 
nothing None
config <module '_roundup_tracker_1.config' from 
'/u/roundup/systems/help/config.
pyo'>
options {'ok_message': [], 'error_message': []}
loop <roundup.cgi.PageTemplates.TALES.SafeMapping 
instance at 0x3aa0f8>
attrs {'tal:condition': 'context/id', 'tal:replace': 'structure 
context/history'
}

A problem occurred in your template "issue.item.html".

[...]
  File "/z/pkgs/roundup-0.7.5/lib/python2.
3/site-packages/roundup/date.py", line
 135, in __init__
    raise ValueError, 'Unknown spec %r'%spec
ValueError: Unknown spec <Date 2004-07-27.00:00:0.
000000>