R1:45f421154179

Fix URI escaping, which should actually be "%s", not "%p"

See <https://discourse.phabricator-community.org/t/projects-workboards-links-issue/2896>.

The documentation on `urisprintf()` isn't very clear here, I'll update it in
a followup. "%p" is for cases like encoding a branch name (which may contain
slashes) as a single path component in a URI.