Fix opening search results for comments

"OC.dirname" removes everything after the last "/", so a path without
slashes is returned without changes. "result.path" does not include
leading nor trailing "/", so when the path is for a file or folder in
the base folder "OC.dirname(result.path)" returns "result.path".

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>