Right now it forgets to reset $wgResourceBasePath, which means it
is inherited from the wikis's (or Jenkins') default settings which
is typically '/w'. That caused parser tests to behave as if pointers
to /extensions were outside /w.
Also update wgScriptPath to be '' instead of '/'. Otherwise this
can cause double-slash prefixed urls.
Change-Id: Ic455d62fca8fcac2c4ecc055cc0d7e311b70a94a
2eeda9bc7d