bugs

[Bamber Ward]

The following ,hopefully, gives you the idea of the problem. The example is 
from the automake manual with slight
alterations to run as a C++ program. Another example, would be configuring 
pecl-cairo downloaded from svn.php.net.
The same relevant line numbers appear in all configure output.However, if I add 
to a macro to find sed for example, the macro succeeds
but line 37 below still appears.
~/jupiter/source_files/ch5-> autoconf --version
autoconf (GNU Autoconf) 2.65
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+/Autoconf: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>, <http://gnu.org/licenses/exceptions.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
operating system Ubuntu 10.4 (2.65-3ubuntu1(lucid)
Written by David J. MacKenzie and Akim Dem-> cd ~/automake/projects/amhello
~/automake/projects/amhello-> ./configure
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for a thread-safe mkdir -p... /bin/mkdir -p
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking for g++... g++
checking whether the C++ compiler works... yes
checking for C++ compiler default output file name... a.out
checking for suffix of executables... 
checking whether we are cross compiling... no
checking for suffix of object files... o
checking whether we are using the GNU C++ compiler... yes
checking whether g++ accepts -g... yes
checking for style of include used by make... GNU
checking dependency style of g++... gcc3
./configure: line 3004: sort: No such file or directory
./configure: line 3001: sed: No such file or directory
configure: creating ./config.status
config.status: creating Makefile
config.status: creating src/Makefile
config.status: creating config.h
config.status: config.h is unchanged
config.status: executing depfiles commands
./configure: line 40: sort: No such file or directory
./configure: line 37: sed: No such file or directory
~/automake/projects/amhello-> 
relevant portion of configure -contains lines 3005 and 3007
   # `set' quotes correctly as required by POSIX, so do not add quotes.
      sed -n "/^[_$as_cr_alnum]*_cv_[_$as_cr_alnum]*=/p"
      ;;
    esac |
    sort
) |
  sed '
     /^ac_cv_env_/b end
     t clear
     :clear
     s/^\([^=]*\)=\(.*[{}].*\)$/test "${\1+set}" = set || &/
     t end
     s/^\([^=]*\)=\(.*\)$/\1=${\1=\2}/
     :end' >>confca
//contains line 37 and 40
esac
fi


as_nl='
'
export as_nl
# Printing a long string crashes Solaris 7 /usr/bin/printf.
as_echo='\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\'
as_echo=$as_echo$as_echo$as_echo$as_echo$as_echo
as_ech