Python points-to: Make sure reachability can skip over if-statements.

python/ql/src/semmle/python/Flow.qll

@@ -1077,6 +1077,22 @@ class BasicBlock extends @py_flow_node {
         not result.(ConditionBlock).controls(this, _)
     }
 
+    /** Holds if flow from this BasicBlock always reaches `succ`
+     */
+    predicate alwaysReaches(BasicBlock succ) {
+        succ = this
+        or
+        strictcount(this.getASuccessor()) = 1
+        and succ = this.getASuccessor()
+        or
+        forex(BasicBlock immsucc |
+            immsucc = this.getASuccessor()
+            |
+            immsucc.alwaysReaches(succ)
+        )
+
+    }
+
 }
 
 private predicate start_bb_likely_reachable(BasicBlock b) {

python/ql/src/semmle/python/pointsto/PointsTo.qll

@@ -220,6 +220,11 @@ cached module PointsToInternal {
         )
         or
         reachableEdge(_, b, context)
+        or
+        exists(BasicBlock pred |
+            reachableBlock(pred, context) and
+            pred.alwaysReaches(b)
+        )
     }
 
     private predicate reachableEdge(BasicBlock pred, BasicBlock succ, PointsToContext context) {

python/ql/test/query-tests/analysis/pointsto/Pruned.expected

@@ -1 +1 @@
-| 1304 |
+| 1284 |