the smallest change to bring back pre-79 behavior

Author: Eh2406

src/internal/partial_solution.rs

@@ -485,12 +485,16 @@ impl<DP: DependencyProvider> PartialSolution<DP> {
             .get(satisfier_package)
             .expect("satisfier package not in incompat");
 
+        let start_term = accum_term.intersection(&incompat_term.negate());
+        let out = satisfier_pa.satisfier(satisfier_package, &start_term);
+
         satisfied_map.insert(
             satisfier_package,
-            satisfier_pa.satisfier(
-                satisfier_package,
-                &accum_term.intersection(&incompat_term.negate()),
-            ),
+            if accum_term.subset_of(incompat_term) {
+                (None, 0, DecisionLevel(1))
+            } else {
+                out
+            },
         );
 
         // Finally, let's identify the decision level of that previous satisfier.

tests/examples.rs

@@ -237,8 +237,8 @@ fn confusing_with_lots_of_holes() {
     };
     assert_eq!(
         &DefaultStringReporter::report(&derivation_tree),
-        r#"Because there is no available version for bar and foo 1 | 2 | 3 | 4 | 5 depends on bar, foo 1 | 2 | 3 | 4 | 5 is forbidden.
-And because there is no version of foo in <1 | >1, <2 | >2, <3 | >3, <4 | >4, <5 | >5 and root 1 depends on foo, root 1 is forbidden."#
+       r#"Because foo 1 | 2 | 3 | 4 | 5 depends on bar and there is no version of foo in <1 | >1, <2 | >2, <3 | >3, <4 | >4, <5 | >5, foo depends on bar.
+And because there is no available version for bar and root 1 depends on foo, root 1 is forbidden."#
     );
     derivation_tree.collapse_no_versions();
     assert_eq!(