bug#3898: 23.1.50; nxml-extend-after-change-region should not return t

When an error occurs in nxml-extend-after-change-region it returns t
which makes font-lock-extend-jit-lock-region-after-change to fail
since it expects a cons with two numbers or nil.

The patch below make the return value nil instead.

Index: nxml-mode.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/nxml/nxml-mode.el,v
retrieving revision 1.18
diff -u -b -r1.18 nxml-mode.el
--- nxml-mode.el	5 Jan 2009 03:22:51 -0000	1.18
+++ nxml-mode.el	21 Jul 2009 18:07:03 -0000
@@ -883,7 +883,8 @@
   (unless nxml-degraded
     (setq nxml-last-fontify-end nil)

-    (nxml-with-degradation-on-error 'nxml-extend-after-change-region
+    (let ((ret (nxml-with-degradation-on-error
+                'nxml-extend-after-change-region
 	(save-excursion
 	  (save-restriction
 	    (widen)
@@ -892,6 +893,7 @@
 		(nxml-with-unmodifying-text-property-changes
                   (nxml-extend-after-change-region1
                    start end pre-change-length)))))))))
+      (when (listp ret) ret))))

 (defun nxml-extend-after-change-region1 (start end pre-change-length)
   (let* ((region (nxml-after-change1 start end pre-change-length))



In GNU Emacs 23.1.50.1 (i386-mingw-nt5.1.2600)
 of 2009-06-30
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4) --no-opt --cflags
-Ic:/g/include -fno-crossjumping'