Parsing problem with comment and block end

I've been trying to improve my preprocessor, and started experimenting
with some admittedly bizarre rc consructs. Some of the results of this
have me stumped. Below is a test harness and output. When a is set
initially to 1, as it is here, I get the log file shown. When a is set
initially to something other than 1, I get a 'missing brace' message.
It seems that, in some circumstances, the closing brace in the comment
is significant, and is parsed as a block end. Is this a bug?


 SHELL=/bin/sh
 MAILDIR=.
 DEFAULT=|
 LOGFILE=log
 NL="
"
 a=1
 :0
 * a ?? 1
 { q= }{   # }
   :0
   * a ?? 1
   { y=|\ 3"4"\\ }
   : 0 E
   { y=|\ 5"6"\\ }
   _=_uuu  # }
   z=abc"z   
   z"def
   x="a b c"\
"  d e f"
   
LOG="#y=$y####{_}=${_}####_=$_####q=$q####z=$z####x=$x####$PROCMAIL_VERSION$NL"
   :0
   /dev/null

Results in this log:

#y=| 34\####{_}=_uuu####_=./pmtest####q=}{####z=abcz   
   zdef####x=a b c  d e f####3.13.1
  Folder: /dev/null                                                           0

-- 
Rik Kabel          Old enough to be an adult              
rik(_at_)netcom(_dot_)com