Visit else in while in any case even if condition is True (PY-28972)

But when condition is `True`, edge to `else` is not created.

python/src/com/jetbrains/python/codeInsight/controlflow/PyControlFlowBuilder.java

@@ -489,11 +489,13 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
       myBuilder.addEdge(myBuilder.prevInstruction, instruction);
     }
     myBuilder.checkPending(instruction);
-    myBuilder.prevInstruction = head;
-    if (elsePart != null && !isStaticallyTrue) {
+
+    if (elsePart != null) {
+      myBuilder.prevInstruction = !isStaticallyTrue ? head : null;
       elsePart.accept(this);
       myBuilder.addPendingEdge(node, myBuilder.prevInstruction);
     }
+
     myBuilder.flowAbrupted();
   }
 

python/testData/codeInsight/controlflow/whiletrueelse.py

@@ -0,0 +1,4 @@
+while True:
+    pass
+else:
+    print("ok")

python/testData/codeInsight/controlflow/whiletrueelse.txt

@@ -0,0 +1,6 @@
+0(1) element: null
+1(2) element: PyWhileStatement
+2(3) READ ACCESS: True
+3(1) element: PyStatementList. Condition: True:true
+4(5) element: PyPrintStatement
+5() element: null

python/testData/refactoring/extractmethod/InterruptedOuterLoop.before.py

@@ -0,0 +1,7 @@
+while True:
+    <selection>
+    while True:
+        pass
+    else:
+        break
+    </selection>

python/testSrc/com/jetbrains/python/PyControlFlowBuilderTest.java

@@ -274,6 +274,11 @@ public class PyControlFlowBuilderTest extends LightMarkedTestCase {
     doTest();
   }
 
+  // PY-28972
+  public void testWhileTrueElse() {
+    doTest();
+  }
+
   private void doTestFirstStatement() {
     final String testName = getTestName(false).toLowerCase();
     configureByFile(testName + ".py");

python/testSrc/com/jetbrains/python/inspections/PyUnreachableCodeInspectionTest.java

@@ -117,6 +117,16 @@ public class PyUnreachableCodeInspectionTest extends PyInspectionTestCase {
     );
   }
 
+  // PY-28972
+  public void testWhileTrueElse() {
+    doTestByText(
+      "while True:\n" +
+      "    pass\n" +
+      "else:\n" +
+      "    <warning descr=\"This code is unreachable\">print(\"ok\")</warning>"
+    );
+  }
+
   @NotNull
   @Override
   protected Class<? extends PyInspection> getInspectionClass() {

python/testSrc/com/jetbrains/python/refactoring/PyExtractMethodTest.java

@@ -270,4 +270,9 @@ public class PyExtractMethodTest extends LightMarkedTestCase {
   public void testCommentsPrecedingSourceStatement() {
     doTest("func");
   }
+
+  // PY-28972
+  public void testInterruptedOuterLoop() {
+    doFail("foo", "Cannot perform refactoring when execution flow is interrupted");
+  }
 }