Basically copying answer from superuser.comsuperuser.com linked by Tom Woodward in comments. I've only changed keycode and url.
It's Greasemonkey script which disables "T" shortcut. Supported by major browsers (extension like Greasemonkey for Firefox/Tampermonkey for Chrome may be needed/useful).
// Your code here...
// ==UserScript==
// @name Disable keyboard shortcuts
// @description Stop websites from highjacking keyboard shortcuts
//
// @run-at document-start
// @include *github.com*
// @grant none
// ==/UserScript==
keycodes = [84] // Keycode for 'T', add more keycodes to disable other key captures
document.addEventListener('keydown', function(e) {
// alert(e.keyCode); //uncomment to find out the keycode for any given key
if (keycodes.indexOf(e.keyCode) != -1)
{
e.cancelBubble = true;
e.stopImmediatePropagation();
}
return false;
});