SFTP: update conditions under which cache for lstat / . is used
SFTP: update conditions under which cache for lstat / . is used

splitice/phpseclib,terrafrost/phpseclib,phpseclib/phpseclib,danog/phpseclib,metaclassing/phpseclib,danog/phpseclib,kenichiii/phpseclib,thaigialai1987/phpseclib,paragonie-scott/phpseclib,metaclassing/phpseclib,splitice/phpseclib,paragonie-scott/phpseclib,kenichiii/phpseclib,thaigialai1987/phpseclib