Comment 6 for bug 71307

GNU diff (and I think other 'diff' programs) use epoch time to indicate that the file was removed. Epoch being Jan 1, 1970 UTC time. (the time when 'timestamp = 0').

Aaron's message is a bit confusing, because GPG doubles up leading '-' characters, it should read:
$ TZ="utc" diff -urN foo bar
diff -urN foo/baz bar/baz
--- foo/baz 2008-06-13 20:53:00.000000000 +0000
+++ bar/baz 1970-01-01 00:00:00.000000000 +0000
@@ -1 +0,0 @@
-baz