'c' and 'r' formatter causes date to be printed twice in views

I am trying to output an ISO-8061-compliant time string in a View, based on the value of a Date field. When I tried to use a custom date format consisting of the single character 'c', which is shorthand for the ISO 8061 format, I noticed that the formatted date string was being printed twice.

After some investigation, I found that the problem stems from incorrect values being assigned by date_formatter_process(). Specifically, for a format string of 'c', this function returns the following array:

Array
(
  ...
  [formatted] => 2012-11-07T22:00:00-06:00
  [formatted_iso] => 2012-11-07T22:00:00-06:00
  [formatted_date] => 2012-11-07T22:00:00-06:00
  [formatted_time] => 2012-11-07T22:00:00-06:00
  [formatted_timezone] => 2012-11-07T22:00:00-06:00
  ...
)

These values eventually make their way to the Date module's theme functions, which essentially do the following:

  ...
  return '<span ... >' . $date . $timezone . '</span>';

$date and $timezone correspond to the [formatted] and [formatted_timezone] values above, respectively. So in the case of a 'c' formatter, the formatted string ends up being printed twice.

I have attached a one-line patch adds a special case for a 'c' formatter in date_formatter_process(). This is the same way that the module currently handles 'U' formatters (which print a standard UNIX timestamp). With this patch applied, the returned array becomes:

Array
(
  ...
  [formatted] => 2012-11-07T22:00:00-06:00
  [formatted_iso] => 2012-11-07T22:00:00-06:00
  [formatted_date] => 2012-11-07T22:00:00-06:00
  [formatted_time] => 
  [formatted_timezone] => 
  ...
)

With this patch applied, 'c' format strings can be used without issue, and the resulting time string is correctly printed only once.