bug#11314: 24.1.50; Regression: incorrect Lisp indentation for `if' with `@@@@@@'

[Drew Adams]

emacs -Q
 
Type this into an Emacs Lisp buffer:
 
(if (alpha beta) C-j aaaaaa C-j bbbbbb
 
You get this:
 
(if (alpha beta)
    aaaaaa
  bbbbbb
 
That is correct.  bbbbbb is indented correctly.
 
Now do the same thing, using @@@@@@ instead of aaaaaa.  This is the
result - bbbbbb is indented incorrectly.
 
(if (alpha beta)
    @@@@@@
    bbbbbb
 
Yet @@@@@@ is a perfectly good symbol/variable name etc.
 
This regression was introduced in Emacs 22.
 

In GNU Emacs 24.1.50.1 (i386-mingw-nt5.1.2600)
 of 2012-04-19 on MARVIN
Bzr revision: 107968 monnier@iro.umontreal.ca-20120419220225-gijdcbfxuiqy5dhb
Windowing system distributor `Microsoft Corp.', version 5.1.2600
Configured using:
 `configure --with-gcc (4.6) --no-opt --enable-checking --cflags
 -ID:/devel/emacs/libs/libXpm-3.5.8/include
 -ID:/devel/emacs/libs/libXpm-3.5.8/src
 -ID:/devel/emacs/libs/libpng-dev_1.4.3-1/include
 -ID:/devel/emacs/libs/zlib-dev_1.2.5-2/include
 -ID:/devel/emacs/libs/giflib-4.1.4-1/include
 -ID:/devel/emacs/libs/jpeg-6b-4/include
 -ID:/devel/emacs/libs/tiff-3.8.2-1/include
 -ID:/devel/emacs/libs/gnutls-3.0.9/include
 -ID:/devel/emacs/libs/libiconv-1.13.1-1-dev/include
 -ID:/devel/emacs/libs/libxml2-2.7.8/include/libxml2'