-p0 patches being phased out

This could be an easy solution #1059990-8: Patch format for Drupal.org is going to change to -p1

Maybe I haven't waited long enough, but I'm still seeing the 25-Feb-2011 dev snapshot.

I don't know what you were planning, but I was thinking of something like this:

<?php
  // Run the command
  $patch = variable_get('patch_manager_path_patch', '/usr/bin/patch');
  foreach (array('-p1', '-p0') as $pn) {
    $cmd = sprintf('%s '.$pn.' --verbose %s -d %s -i %s',
      $patch,
      $flags,
      escapeshellarg($root),
      escapeshellarg($patchfile)
    );
    exec($cmd, $output, $ret);
    if (!$ret) break;
  }
?>

Both -p1 and -p0 patches are going to be circulating for a while. Some developers won't have heard about the change. Many -p0 patches are already in the issue queues or distributed with modules. If you drop support for either standard, your own issue queue could be flooded with support requests from users wondering why their patches didn't apply. Especially since GUI tools like Patch Manager appeal to the less technically inclined.

I have rolled #4 into a patch and tested it with every combination of core, contrib, -p1, -p0, apply, revert.

The above patch fails to handle the exception where a patch is partially applied. Here is a correction.