openssh unix dev - Aug 2012 - Question about -b mode of sftp(1) and auto-chdir behaviour

Hello,
i'm curious to know wether the automatic chdir behaviour of sftp(1)
in batch mode is a side-effect of the current implementation, or
if it's instead a regular feature.  And, if it's indeed the latter,
wether there is any compatibility problem if one would actually
rely on it?
I'll attach a copy+paste diff to document this nice feature in
sftp.1, just for the hoped-for case.
Thank you!  ..and ciao,

--steffen
-------------- next part --------------
diff --git a/sftp.1 b/sftp.1
--- a/sftp.1
+++ b/sftp.1
@@ -57,7 +57,11 @@
 .Oc
 .Nm sftp
 .Fl b Ar batchfile
-.Oo Ar user Ns @ Oc Ns Ar host
+.Oo
+.Ar user Ns @ Oc Ns
+.Ar host Ns Oo : Ns Ar dir Ns
+.Op Ar /
+.Oc
 .Sh DESCRIPTION
 .Nm
 is an interactive file transfer program, similar to

|Hello,
 |i'm curious to know wether the automatic chdir behaviour of sftp(1)
 |in batch mode is a side-effect of the current implementation, or
 |if it's instead a regular feature.  And, if it's indeed the latter,
 |wether there is any compatibility problem if one would actually
 |rely on it?
 |I'll attach a copy+paste diff to document this nice feature in
 |sftp.1, just for the hoped-for case.
 |Thank you!  ..and ciao,
 |
 |--steffen

Well, it seems that those are nice but wanted side effects from
before start:

  |?146%2[steffen at sherwood openssh.hg]$ hg s-log -r 5792
  || Rev:  || 5792:ddc05befc083   
  || Auth: djm
  || Date: Tue, 27 Jan 2004 10:22:00 +0000
  |
  |- djm at cvs.openbsd.org 2004/01/27 10:08:10
  |     [sftp.c]
  |     reorder parsing so user:skey at host:file works (bugzilla #777)
  |     patch from admorten AT umich.edu; ok markus@
  |
  |?0%2[steffen at sherwood openssh.hg]$ hg s-log -r 5877
  || Rev:  || 5877:6e27a7ce8139   
  || Auth: djm
  || Date: Wed, 18 Feb 2004 03:30:55 +0000
  |
  |- djm at cvs.openbsd.org 2004/02/17 11:03:08
  |     [sftp.c]
  |     sftp.c and sftp-int.c, together at last; ok markus@

Great if that would be documented...
Btw. i've recognized that, when ssh is used with -M option,
other sessions inherit the PW entry of that session.  Happens
that i've changed the shell via 'chpass -s' due to debugging
and the new login still presented the old shell.  grep(1)ping
for pw_(chan|expi) in openssh.hg didn't helped so much.
Shouldn't this (GNU configure is the one which triggers the
most when grep(1)ed) be taken into account even under Control*?
I still haven't read the SSH related RFCs, and it seems that
a connection is heavily related with PW stuff, on the other hand.
Thanks and ciao,

--steffen