Bizarre self-referential warning sign

This sign over an escalator apparently warns people not to bump their head on the sign.

This is one of the most bizarre signs I have ever encountered ... IT'S A SIGN ABOUT THE SIGN ITSELF ... The logic behind the existence of this self-referential sign escapes me! What is it for? Why is it there? Did whoever put it up realize that if there were no sign, there would be no need to warn about it? Is this a joke from the developers? Is it a lesson in recursiveness? Is it a philosophical prop?

My guess: there's a sign on the other side of this that's not self-referential. Link (thanks, jaybird!)

Reader comment: Chris26 says: "In regards to that sign, there is actually a method to the madness...

"That triangle 'blocker' is there because if someone was leaning over the side of the escalator, I'm sure they would rather be dinked on the side of the head by a orange plastic warning sign rather than their neck getting caught in the corner where the banister meets the ceiling while the escalator continues to drag their body up.

"The picture says 'Mind the blocker' while the blocker says 'Mind that you dont break your neck.'"