$_ = '/spam';
s#^.*((?<=^/spam/).*|(?<=^/spam))$#/$1#;
$_ = '/spam/';
s#^.*((?<=^/spam/).*|(?<=^/spam))$#/$1#;
$_ = '/spam/one';
s#^.*((?<=^/spam/).*|(?<=^/spam))$#/$1#;
$_ = '/spam/one/two';
s#^.*((?<=^/spam/).*|(?<=^/spam))$#/$1#;
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