FYI: I'm using 7.12.1 as well, through HomeBrew, and the problem remains, even though others seem to have had success with this.
I described the steps I followed
here.
Adding the "--eval-command=set startup-with-shell off" to Lazarus > Tools > Options > Debugger > Debugger_Startup_Options resolved it for me.
Adding "set startup-with-shell off" (without the quotes) to ~/.gdbinit did not seem to work on my setup.