Python: fix shared CFG exception-handler reachability

python/ql/lib/semmle/python/controlflow/internal/AstNodeImpl.qll

@@ -1724,7 +1724,7 @@ private module Input implements InputSig1, InputSig2 {
     always = true
     or
     mayThrow(ast) and
-    n.isIn(ast) and
+    n.injects(ast) and
     c.asSimpleAbruptCompletion() instanceof ExceptionSuccessor and
     always = false
   }

python/ql/test/library-tests/ControlFlow/shared-cfg-exceptions/ExceptionReachabilityTest.ql

@@ -0,0 +1,29 @@
+/**
+ * Inline-expectations test for exception-handler reachability in the shared CFG.
+ */
+
+import python
+import semmle.python.controlflow.internal.AstNodeImpl as CfgImpl
+import semmle.python.controlflow.internal.Cfg as Cfg
+import utils.test.InlineExpectationsTest
+
+module ExceptionReachabilityTest implements TestSig {
+  string getARelevantTag() { result = "exception-handler" }
+
+  predicate hasActualResult(Location location, string element, string tag, string value) {
+    exists(
+      Expr source, ExceptStmt handler, Cfg::ControlFlowNode sourceCfg,
+      Cfg::ControlFlowNode handlerEntry
+    |
+      sourceCfg.getNode() = source and
+      handlerEntry = sourceCfg.getAnExceptionalSuccessor() and
+      CfgImpl::astNodeToPyNode(handlerEntry.getAstNode()) = handler and
+      location = source.getLocation() and
+      element = source.toString() and
+      tag = "exception-handler" and
+      value = handler.getType().toString()
+    )
+  }
+}
+
+import MakeTest<ExceptionReachabilityTest>

python/ql/test/library-tests/ControlFlow/shared-cfg-exceptions/test.py

@@ -0,0 +1,12 @@
+def generator():
+    try:
+        yield  # $ exception-handler=GeneratorExit
+    except GeneratorExit:
+        return
+
+
+def load_module():
+    try:
+        import unavailable_module  # $ exception-handler=ImportError
+    except ImportError:
+        return None