Provide @href value as fallback for branch filtering
Provide @href value as fallback for branch filtering

Per https://github.com/dita-ot/dita-ot/issues/2826

Amends c94268b7.

Signed-off-by: Roger Sheen <a61a1add71dadc74037ae5e44ee30713db9a7451@infotexture.net>

infotexture/docs,dita-ot/docs,infotexture/docs