Homebrew GnuPG vs. GPG Mail
I have paid for and installed GPG Suite integration with Apples Mail application.
Homebrew offers gnupg, so I have observed that the two tools clash on some of the command line tools such as:
gpggpg-agent
As both tools install into /usr/local/bin
Homebrew provides information and a remedy when the conflict occurs
$ brew link --overwrite --dry-run gnupg
Would remove:
/usr/local/bin/gpg -> /usr/local/MacGPG2/bin/gpg2
/usr/local/bin/gpg-agent -> /usr/local/MacGPG2/bin/gpg-agent
So the remedy is:
$ brew link --overwrite gnupg
Linking /usr/local/Cellar/gnupg/2.3.2... 73 symlinks created.
I am unsure of this causes any additional trouble, but I have not experienced any just yet and I have not tried out the installation/upgrade in the opposite order.