You bunch of fucking dumbasses.  It's not that the system time was set to -1.  It's that in PHP, any function that is supposed to return a Unix-style timestamp (e.g., filemtime) returns undefined on failure (as when you try to get filestats from an OS that doesn't support it), which the system interprets as -1 seconds when it tries to convert it to a date.  As others pointed out, time begins at 00:00:00 on January 1st, 1970, so -1 seconds comes out 11:59:59 31 December 1969.  GOD YOU ARE ALL MORONS. 
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