Thanks. I'm not using git with TextMate and there's no shortcut for it, so seems unlikely.
I assume I'm inadvertently applying some shortcut. More than irritating since the end of the file gets chopped off without my realizing it and I'm relying on manual saving.
Sounds like an 'git stash apply' happened.
I'm working on a Ruby script in TextMate 2 and all of a sudden I'm seeing the end of my files disappear and inserted midline is ">>>>>>> External Changes" and from there on everything is deleted. The only thing that I've knowingly changed is I've started to use Bookmarks. Therefore Cmd-F2 and shift-F2.