Description:
------------
The values of static variables within a tick handler (registered with register_tick_function) persist across multiple invocations of the script.

You can run and re-run this script as many times as you like; the static variable value keeps growing.

This bug is similar to #11536 and #17283, but those were closed due to lack of response.

Reproduce code:
---------------
      1 function heartbeat($return = false) {
      2     static $static = 0;
      3            $auto   = 0;
      4
      5     if ($return) {
      6         return "static=[$static]\nauto=[$auto]\n";
      7     } else {
      8         $static++;
      9         $auto++;
     10     }
     11
     12 }
     13
     14 register_tick_function('heartbeat');
     15 declare (ticks = 1) {
     16 }
     17 echo heartbeat(true);

Expected result:
----------------
At the end of each run of this script, the value of $static should be 1 and the value of $auto should be 0.

According to the documentation, the tick function (heartbeat) will be called for every tick (1) statements ecxecuted in the declare block, PLUS 1 for the declare close curly (line 16).  Because there are 0 statements in the block, I expect 0/1 + 1 callbacks to hearbeat.

Consequently, $static should have a value of 1 (incremented once) and $auto should have a value of 0 (incremented once but looses value after each call) when explicitly called on line 18.

If you set ticks = 2, I would expect 0/2 + 1 callbacks. Because there are no statements in the block, ANY value of ticks should still execute only once.  Ergo, regardless of the ticks setting, $static should still have a value of 1 and $auto a value of 0.

Actual result:
--------------
At the end of each run of this script, the value of $static increases relative to the value it had at the LAST run, and $auto remains at 0 always.  Furthermore, "LAST" appears to refer to the last value in the particular Apache child. If I set Apache to 1 child only, the value always increases relative to that single value, rather than bouncing around.

In other words, the static variable within heartbeat appears to retain its value ACROSS invocations. While this would otherwise be a nice feature, the value bounces around (ie is not monotonically increasing).

Also, with ticks = 1, the value of the static variable appears to increase by 2 each time: 2, 4, 6, 8, etc. With ticks = 2, $static increases by 1: 1, 2, 3, etc.  With ticks >= 3, $static doesn't increase at all: 0, 0, 0, etc.
(This may be a separate bug, but I'd rather just mention it here)