Set that a type is from docblock when substituting in docblock atomic type

src/Psalm/Context.php

@@ -213,6 +213,11 @@ class Context
                     // also never allow ourselves to remove all types from a union
                     if ((string)$old_type !== (string)$new_type && ($new_type || count($context_type->types) > 1)) {
                         $context_type->substitute($old_type, $new_type);
+
+                        if ($new_type && $new_type->from_docblock) {
+                            $context_type->setFromDocblock();
+                        }
+
                         $updated_vars[$var] = true;
                     }
                 }

tests/RedundantConditionTest.php

@@ -95,6 +95,25 @@ class RedundantConditionTest extends TestCase
                         }
                     }',
             ],
+            'noRedundantConditionTypeReplacementWithDocblock' => [
+                '<?php
+                    class A {}
+
+                    /**
+                     * @return A
+                     */
+                    function getA() {
+                        return new A();
+                    }
+
+                    $maybe_a = rand(0, 1) ? new A : null;
+
+                    if ($maybe_a === null) {
+                        $maybe_a = getA();
+                    }
+
+                    if ($maybe_a === null) {}',
+            ],
         ];
     }