Apply ljb's patch to prevent both memory leak and core dump during

connection shutdown.  This is a grotty workaround for a Tcl bug, but
said bug has been there long enough that I'm not holding my breath
for a real fix.  Per discussions and testing from ljb and g.hintermayer.

src/interfaces/libpgtcl/pgtclId.c

@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtclId.c,v 1.38 2002/12/30 22:10:54 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtclId.c,v 1.39 2003/02/01 00:07:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -295,17 +295,19 @@ PgDelConnectionId(DRIVER_DEL_PROTO)
 	 * the socket itself!
 	 *
 	 * XXX Unfortunately, while this works fine if we are closing due to
-	 * explicit pg_disconnect, Tcl versions through 8.3.3 dump core if we
-	 * try to do it during interpreter shutdown.  Not clear why, or if
-	 * there is a workaround.  For now, accept leakage of the (fairly
-	 * small) amount of memory taken for the channel state representation.
-	 * Note we are not leaking a socket, since libpq closed that already.
+	 * explicit pg_disconnect, all Tcl versions through 8.4.1 dump core
+	 * if we try to do it during interpreter shutdown.  Not clear why.
+	 * For now, we kill the channel during pg_disconnect, but during interp
+	 * shutdown we just accept leakage of the (fairly small) amount of memory
+	 * taken for the channel state representation.
+	 * (Note we are not leaking a socket, since libpq closed that already.)
+	 * We tell the difference between pg_disconnect and interpreter shutdown
+	 * by testing for interp != NULL, which is an undocumented but apparently
+	 * safe way to tell.
 	 */
-#ifdef NOT_USED
 #if TCL_MAJOR_VERSION >= 8
-	if (connid->notifier_channel != NULL)
+	if (connid->notifier_channel != NULL && interp != NULL)
 		Tcl_UnregisterChannel(NULL, connid->notifier_channel);
-#endif
 #endif
 
 	/*