phpbb_own_realpath() doesn't always replicate realpath() behaviour

File: t/ta

Target: /

php realpath: /

phpbb realpath:

os realpath: /

File: t/tb

Target: .

php realpath: /home/pie/apps/rcf/webroot/forums/t

phpbb realpath: .

os realpath: /home/pie/apps/rcf/webroot/forums/t

File: t/tc

Target: ..

php realpath: /home/pie/apps/rcf/webroot/forums

phpbb realpath: ..

os realpath: /home/pie/apps/rcf/webroot/forums

File: t/td

Target: d

php realpath: /home/pie/apps/rcf/webroot/forums/t/d

phpbb realpath:

os realpath: /home/pie/apps/rcf/webroot/forums/t/d

File: t/te

Target: ./d

php realpath: /home/pie/apps/rcf/webroot/forums/t/d

phpbb realpath:

os realpath: /home/pie/apps/rcf/webroot/forums/t/d

File: t/tf

Target: ../t/d

php realpath: /home/pie/apps/rcf/webroot/forums/t/d

phpbb realpath:

os realpath: /home/pie/apps/rcf/webroot/forums/t/d

pie@snap forums % ls -l t

-rw-r--r--  1 pie  pie    0 Apr 10 23:36 d

lrwxr-xr-x  1 pie  pie    1 Apr 10 23:36 ta -> /

lrwxr-xr-x  1 pie  pie    1 Apr 10 23:36 tb -> .

lrwxr-xr-x  1 pie  pie    2 Apr 10 23:36 tc -> ..

lrwxr-xr-x  1 pie  pie    1 Apr 10 23:36 td -> d

lrwxr-xr-x  1 pie  pie    3 Apr 10 23:36 te -> ./d

lrwxr-xr-x  1 pie  pie    6 Apr 10 23:36 tf -> ../t/d