Removing mac’s downloaded application security warning

I recently ran into a problem where a program on my mac wouldn't save my acknowledgment of the "X is an application that was downloaded from the Internet" warning, despite my repeatedly confirming I really wanted to open the application.

I think the problem stems from the fact that I installed the program for all users from another account, so the permissions were all wonky and wouldn't save the new xattr.  Here's the solution:

$ cd /path/to/application
# View all files with extended attributes
$ ls -lsa
# To see the files that are quarantined:
$ xattr -l * | grep com.apple.quarantine
# Remove the extended attributes
$ sudo xattr -d com.apple.quarantine \
    $(xattr -l * | grep com.apple.quarantine | \
       awk -F: '{print $1}')