String#start_with? return wrong result for Regexp patterns containing /\K/
String#start_with? unexpectedly reports true when the pattern Regexp contains
/\K/ (lookbehind) operator and the lookbehind pattern matches the beginning of
"hello".start_with?(/h\Ke/) # => true (unexpected)
In this example,
/h\Ke/ matches "hello", but it's not considered as a match at the beginning of the string by the other Regexp operations (e.g.
$~.begin(0) == 1).