Fix bug in DROP OWNED BY.

Commit 6566133 broke the case where
the role passed to DROP OWNED BY owns a database.

Report by Rushabh Lathia, who also provided a patch, but this patch
takes a slightly different approach to fixing the problem.

Discussion: http://postgr.es/m/CAGPqQf2vO+nbo=3yAdZ8v26Rbug7bY4YjPaPLZx=L1NZ9-CC3w@mail.gmail.com

Author: robertmhaas

src/backend/catalog/pg_shdepend.c

@@ -1412,19 +1412,28 @@ shdepDropOwned(List *roleids, DropBehavior behavior)
 						break;
 					}
 					/* FALLTHROUGH */
+
 				case SHARED_DEPENDENCY_OWNER:
-					/* Save it for deletion below */
-					obj.classId = sdepForm->classid;
-					obj.objectId = sdepForm->objid;
-					obj.objectSubId = sdepForm->objsubid;
-					/* as above */
-					AcquireDeletionLock(&obj, 0);
-					if (!systable_recheck_tuple(scan, tuple))
+					/*
+					 * Save it for deletion below, if it's a local object or a
+					 * role grant. Other shared objects, such as databases,
+					 * should not be removed here.
+					 */
+					if (sdepForm->dbid == MyDatabaseId ||
+						sdepForm->classid == AuthMemRelationId)
 					{
-						ReleaseDeletionLock(&obj);
-						break;
+						obj.classId = sdepForm->classid;
+						obj.objectId = sdepForm->objid;
+						obj.objectSubId = sdepForm->objsubid;
+						/* as above */
+						AcquireDeletionLock(&obj, 0);
+						if (!systable_recheck_tuple(scan, tuple))
+						{
+							ReleaseDeletionLock(&obj);
+							break;
+						}
+						add_exact_object_address(&obj, deleteobjs);
 					}
-					add_exact_object_address(&obj, deleteobjs);
 					break;
 			}
 		}

src/bin/scripts/t/020_createdb.pl

@@ -158,4 +158,22 @@
 	qr/statement: CREATE DATABASE foobar7 STRATEGY file_copy TEMPLATE foobar2/,
 	'create database with FILE_COPY strategy');
 
+# Create database owned by role_foobar.
+$node->issues_sql_like(
+	[ 'createdb', '-T', 'foobar2', '-O', 'role_foobar', 'foobar8' ],
+	qr/statement: CREATE DATABASE foobar8 OWNER role_foobar TEMPLATE foobar2/,
+	'create database with owner role_foobar');
+($ret, $stdout, $stderr) = $node->psql(
+	'foobar2',
+	'DROP OWNED BY role_foobar;',
+	on_error_die => 1,
+);
+ok($ret == 0, "DROP OWNED BY role_foobar");
+($ret, $stdout, $stderr) = $node->psql(
+	'foobar2',
+	'DROP DATABASE foobar8;',
+	on_error_die => 1,
+);
+ok($ret == 0, "DROP DATABASE foobar8");
+
 done_testing();