MDL-87657 cohort: fix permission check for viewing system cohorts.

The problem manifested itself in custom reports using the corresponding
cohort field filter, which didn't reload current form values due to
incorrect context tree comparison.

public/cohort/lib.php

@@ -363,7 +363,7 @@ function cohort_can_view_cohort($cohortorid, $currentcontext) {
         $cohort = $cohortorid;
     }
 
-    if ($cohort && in_array($cohort->contextid, $currentcontext->get_parent_context_ids())) {
+    if ($cohort && in_array($cohort->contextid, $currentcontext->get_parent_context_ids(true))) {
         if ($cohort->visible) {
             return true;
         }

public/cohort/tests/lib_test.php

@@ -943,6 +943,21 @@ final class lib_test extends \advanced_testcase {
         }
     }
 
+    /**
+     * Test whether user can view cohort
+     *
+     * @covers ::cohort_can_view_cohort
+     */
+    public function test_cohort_can_view_cohort(): void {
+        $this->resetAfterTest();
+        $this->setAdminUser();
+
+        $context = \context_system::instance();
+        $cohort = $this->getDataGenerator()->create_cohort(['contextid' => $context->id]);
+
+        $this->assertTrue(cohort_can_view_cohort($cohort, $context));
+    }
+
     /**
      * Test the behaviour of cohort_get_cohort().
      *