5.0 vs 5.1 remote command execution

[Kaizaad Bilimorya]

Hello,

I am experiencing some strange behaviour that I am hoping someone can 
shed some light on.

OS and kernel:
Red Hat Enterprise Linux AS release 4 (Nahant Update 5)
Linux host135 2.6.9-67.9hp.7sp.XCsmp #1 SMP Thu Jul 3 18:55:59 EDT 2008 x86_64 x86_64 x86_64 GNU/Linux


built both openssh-5.0p1 and openssh-5.1p1 with the following options:
./configure --prefix=/usr --libexecdir=/usr/libexec/openssh --localstatedir=/var/empty/sshd \
--sysconfdir=/etc/ssh --with-pam --with-md5-passwords --with-zlib=/home/XXX/software/zlib-1.2.3 \
--with-tcp-wrappers


With everything else being identical and just swapping the sshd binaries, 
I noticed the following:

# ssh -v host135
debug1: match: OpenSSH_5.0 pat OpenSSH*
...snip
# ssh host135 'echo $PATH'
/opt/octave/current:/opt/mpiblast/current/bin:/opt/lammps/current/bin:/opt/dlpoly/current/execute:
...snip

# ssh -v host135
debug1: match: OpenSSH_5.1 pat OpenSSH*
...snip
# ssh host135 'echo $PATH'
/usr/bin:/bin:/usr/sbin:/sbin


According to the docs, the behaviour exhibited by v5.1 is correct, remote 
command execution should not process the user's login shell and env. But 
why was this happening in v5.0? I can't find anything in the 5.1 change 
log that explains this change in behaviour.

thanks
-k