When you try to tab-complete a directory name, it completes the name and adds a space after it instead of a slash, so you then have to backspace away the space and type a slash before you can type the file name (or, God forbid, another directory name, then do that all over again).
$ scap sync-file wmf-[TAB] $ scap sync-file wmf-config $ scap sync-file wmf-config Ini [ugh] [backspace backspace backspace backspace] $ scap sync-file wmf-config/Ini[TAB] $ scap sync-file wmf-config/InitialiseSettings.php
vs
$ ls wmf-[TAB] $ ls wmf-config/ $ ls wmf-config/Ini[TAB] $ ls wmf-config/InitialiseSettings.php