* add rule
* p = direct literal; always < 0 for installed rpm rules
* d, if < 0 direct literal, if > 0 offset into whatprovides, if == 0 rule is assertion (look at p only)
*
*
* A requires b, b provided by B1,B2,B3 => (-A|B1|B2|B3)
*
* p < 0 : pkg id of A
* d > 0 : Offset in whatprovidesdata (list of providers of b)
*
* A conflicts b, b provided by B1,B2,B3 => (-A|-B1), (-A|-B2), (-A|-B3)
* p < 0 : pkg id of A
* d < 0 : Id of solvable (e.g. B1)
*
* d == 0: unary rule, assertion => (A) or (-A)
*
* Install: p > 0, d = 0 (A) user requested install
* Remove: p < 0, d = 0 (-A) user requested remove (also: uninstallable)
* Requires: p < 0, d > 0 (-A|B1|B2|...) d: <list of providers for requirement of p>
* Updates: p > 0, d > 0 (A|B1|B2|...) d: <list of updates for solvable p>
* Conflicts: p < 0, d < 0 (-A|-B) either p (conflict issuer) or d (conflict provider) (binary rule)
* also used for obsoletes
* ?: p > 0, d < 0 (A|-B)
* No-op ?: p = 0, d = 0 (null) (used as policy rule placeholder)
*
* resulting watches:
* ------------------
* Direct assertion (no watch needed)( if d <0 ) --> d = 0, w1 = p, w2 = 0
* Binary rule: p = first literal, d = 0, w2 = second literal, w1 = p
* every other : w1 = p, w2 = whatprovidesdata[d];
* Disabled rule: w1 = 0
*
* always returns a rule for non-rpm rules



p > 0, d = 0, (A), w1 = p, w2 = 0
p < 0, d = 0, (-A), w1 = p, w2 = 0
p !=0, d = 0, (p|q), w1 = p, w2 = q