Description:
------------
timezone_open() accepts undocumented/nonsense/partial timezones.
The docs say "One of the supported timezone names or an offset value" but accepts seemingly nonsense timezones without failure, and timezones found in the first non-whitespace block in the argument string.

Test script:
---------------
$tz = timezone_open("x UTC");
echo '"x UTC" = '; var_dump($tz);

$tz = timezone_open("c");
echo '"c" = '; var_dump($tz);

$tz = timezone_open("xx UTC");
echo '"xx UTC" = '; var_dump($tz);

$tz = timezone_open("xUTC");
echo '"xUTC" = '; var_dump($tz);

$tz = timezone_open("UTCx");
echo '"UTCx" = '; var_dump($tz);

$tz = timezone_open("UTC xx");
echo '"UTC xx" = '; var_dump($tz);


Expected result:
----------------
"x UTC" = bool(false)
"c" = bool(false)
"xx UTC" = bool(false)
"xUTC" = bool(false)
"UTCx" = bool(false)
"UTC xx" = bool(false)


Actual result:
--------------
"x UTC" = object(DateTimeZone)#127 (2) {
  ["timezone_type"]=>
  int(2)
  ["timezone"]=>
  string(1) "X"
}
"c" = object(DateTimeZone)#128 (2) {
  ["timezone_type"]=>
  int(2)
  ["timezone"]=>
  string(1) "C"
}
"xx UTC" = bool(false)
"xUTC" = bool(false)
"UTCx" = bool(false)
"UTC xx" = object(DateTimeZone)#128 (2) {
  ["timezone_type"]=>
  int(3)
  ["timezone"]=>
  string(3) "UTC"
}