Fix missing commit/end transaction in connection manager (mailbox connection)

bramble-core/src/main/java/org/briarproject/bramble/plugin/ConnectionManagerImpl.java

@@ -268,8 +268,9 @@ class ConnectionManagerImpl implements ConnectionManager {
 				return;
 			}
 			contactId = ctx.getContactId();
+			Transaction txn = null;
 			try {
-				Transaction txn = db.startTransaction(true);
+				txn = db.startTransaction(true);
 				ContactType type = db.getContactType(txn, contactId);
 				switch (type) {
 					case MAILBOX_OWNER:
@@ -278,11 +279,16 @@ class ConnectionManagerImpl implements ConnectionManager {
 						return;
 					default:
 				}
+				db.commitTransaction(txn);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				disposeReader(true, true);
 				return;
+			}finally {
+				if (txn != null)
+					db.endTransaction(txn);
 			}
+
 			connectionRegistry.registerConnection(contactId, transportId, true);
 			// Start the outgoing session on another thread
 			ioExecutor.execute(this::runOutgoingSession);