来自strtotime格式("g:i A")的意外结果，参数少于4位

Question

尝试使用strtotime格式化时间，但收到意外结果。(运行PHP 7.18)我被提示提供更多细节，但我不知道如何问一个更长的问题，儿子，请忽略这些多余的言辞。

<?php;
$time = 1000;
echo date("g:i A", strtotime($time)).'<br>';
# yields 10:00 AM  OK

$time = 2359;
echo date("g:i A", strtotime($time)).'<br>';
# yields 11:59 PM  OK

$time = 900;
echo date("g:i A", strtotime($time)).'<br>';
# expected 09:00  BUT
#yields 4:00 PM   

$time = 5;
echo date("g:i A", strtotime($time)).'<br>';
# expected 00:05  BUT
#yields 4:00 PM  

$time = 0630;
echo date("gg:i A", strtotime($time));
# tentatively expected 6:30 AM BUT
#yields 4:00 PM