Test clause/2 with single-variable body.
Test clause/2 with single-variable body.

mndrix/swipl-devel,edechter/swipl-devel,koryonik/swipl-devel,mndrix/swipl-devel,jn7163/swipl-devel,mndrix/swipl-devel,jn7163/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel,edechter/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel,mndrix/swipl-devel,jn7163/swipl-devel,mndrix/swipl-devel