reverted:
--- b/core/modules/system/tests/modules/entity_test/update/status_report_8001.inc
+++ a/core/modules/system/tests/modules/entity_test/update/status_report_8001.inc
@@ -10,8 +10,4 @@
  */
 function entity_test_update_8001() {
   // Empty update, we just want to trigger an error in the status report.
-
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
diff -u b/core/modules/system/tests/modules/entity_test/update/status_report_8002.inc b/core/modules/system/tests/modules/entity_test/update/status_report_8002.inc
--- b/core/modules/system/tests/modules/entity_test/update/status_report_8002.inc
+++ b/core/modules/system/tests/modules/entity_test/update/status_report_8002.inc
@@ -13,7 +13,3 @@
 function entity_test_update_8002() {
-  // Empty update, we just want to trigger an update run.
-
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
+  // Empty update, we just want to trigger an error in the status report.
 }
reverted:
--- b/core/modules/system/tests/modules/update_test_0/update_test_0.install
+++ a/core/modules/system/tests/modules/update_test_0/update_test_0.install
@@ -9,25 +9,16 @@
  * Dummy update_test_0 update 8001.
  */
 function update_test_0_update_8001() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
 
 /**
  * Dummy update_test_0 update 8002.
  */
 function update_test_0_update_8002() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
 
 /**
  * Dummy update_test_0 update 8003.
  */
 function update_test_0_update_8003() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
reverted:
--- b/core/modules/system/tests/modules/update_test_1/update_test_1.install
+++ a/core/modules/system/tests/modules/update_test_1/update_test_1.install
@@ -40,25 +40,16 @@
  * Dummy update_test_1 update 8001.
  */
 function update_test_1_update_8001() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
 
 /**
  * Dummy update_test_1 update 8002.
  */
 function update_test_1_update_8002() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
 
 /**
  * Dummy update_test_1 update 8003.
  */
 function update_test_1_update_8003() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
reverted:
--- b/core/modules/system/tests/modules/update_test_2/update_test_2.install
+++ a/core/modules/system/tests/modules/update_test_2/update_test_2.install
@@ -38,25 +38,16 @@
  * Dummy update_test_2 update 8001.
  */
 function update_test_2_update_8001() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
 
 /**
  * Dummy update_test_2 update 8002.
  */
 function update_test_2_update_8002() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
 
 /**
  * Dummy update_test_2 update 8003.
  */
 function update_test_2_update_8003() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
reverted:
--- b/core/modules/system/tests/modules/update_test_3/update_test_3.install
+++ a/core/modules/system/tests/modules/update_test_3/update_test_3.install
@@ -21,7 +21,4 @@
  * Dummy update_test_3 update 8001.
  */
 function update_test_3_update_8001() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
reverted:
--- b/core/modules/system/tests/modules/update_test_failing/update_test_failing.install
+++ a/core/modules/system/tests/modules/update_test_failing/update_test_failing.install
@@ -19,8 +19,4 @@
  */
 function update_test_failing_update_8002() {
   // This hook won't ever run.
-
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
reverted:
--- b/core/modules/system/tests/modules/update_test_invalid_hook/update_test_invalid_hook.install
+++ a/core/modules/system/tests/modules/update_test_invalid_hook/update_test_invalid_hook.install
@@ -9,7 +9,4 @@
  * Hook implementation using the reserved schema version 8000.
  */
 function update_test_invalid_hook_update_8000() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
reverted:
--- b/core/modules/system/tests/modules/update_test_postupdate/update_test_postupdate.install
+++ a/core/modules/system/tests/modules/update_test_postupdate/update_test_postupdate.install
@@ -9,7 +9,4 @@
  * Normal update_N() function.
  */
 function update_test_postupdate_update_8001() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
reverted:
--- b/core/modules/system/tests/modules/update_test_with_7x/update_test_with_7x.install
+++ a/core/modules/system/tests/modules/update_test_with_7x/update_test_with_7x.install
@@ -9,18 +9,12 @@
  * Dummy update_test_with_7x update 7200.
  */
 function update_test_with_7x_update_7200() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
 
 /**
  * Dummy update_test_with_7x update 7201.
  */
 function update_test_with_7x_update_7201() {
-  // Use of hook_post_update_NAME instead to clear the cache.
-  // The use of hook_update_N to clear the cache has been deprecated
-  // see https://www.drupal.org/node/2960601 for more details.
 }
 
 /**