unintended interactive debugger behavior with `shopt -s extdebug`

[Mike Frysinger]

we use "extdebug" in our scripts to get the extended BASH_ARGC and BASH_ARGV 
info so that when an error does occur, we can construct and display a useful 
backtrace of where things fell apart and how the script got there.  this has 
significantly cut down time otherwise spent on manual debugging.

unfortunately, using `shopt -s extdebug` implies --debugger in subshells -- 
something we most certainly do not want.  but there doesnt seem to be a way to 
get what we want (BASH_ARG{C,V}) without having the interactive debugger 
launch on us with "hacky" scripts.  i'm pretty sure this behavior is 
unintended ... at least, the bash docs dont say anywhere that extdebug implies 
the same behavior as when bash is run with --debugger.

if this is actually intended behavior, can we get said behavior changed ?  or 
an option so that we can control this ?

some real world examples would be openssl and rsstool.  they have some shell 
scripts which can be passed through other things.  openssl can be run through 
perl and a POSIX shell.  rsstool can be run through a C compiler and a POSIX 
shell.  but they have to forgo the shebang at the top of the file in order to 
get this behavior.  which leads to the problem ...

a simple example ... while i am running the top shell interactively, the same 
behavior can be seen with non-interactive shell scripts:

$ cat test.sh
echo moo
$ ./test.sh
moo

$ shopt -s extdebug
$ ./test.sh
 debugger, release

Copyright 2002, 2003, 2004, 2006, 2007, 2008 Rocky Bernstein
This is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.

Bourne-Again Shell Debugger, release

Copyright 2002, 2003, 2004, 2006, 2007, 2008 Rocky Bernstein
This is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.

 debugger, release

Copyright 2002, 2003, 2004, 2006, 2007, 2008 Rocky Bernstein
This is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.

(/home/vapier/test.sh:1):
1:      echo moo
bashdb<0>
-mike

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