manually patching a port gets overwritten when the tree updates

Hi,

I thought 'git stash' would take care of this but it doesn't.

Sometimes a port breaks then a PR is raised and then sometimes someone
posts a patch. I'll apply it to my ports tree 'default' in poudriere and
build the port. If it builds ok I'll run 'git stash' then 'poudriere
ports -u -v' and the ports tree updates.

If I don't run 'git stash' the update will fail.

But if I try to build the affected port again, after successfully
updating the tree, it's as if the patch was never applied. The same sort
of thing happens with the usual ports tree (in other words, without
poudriere in the equation)

I want manually applied patches to remain applied, and I want my ports
tree to stay as current as possible. How is this accomplished?

thanks,
-- 
J.