[syslinux] chain.c32 Insane primary (MBR) partition

[Ady]

The following boot entries:
#
COM32 chain.c32
APPEND fs ntldr=/bootmgr
#

or:
#
COM32 chain.c32
APPEND hd0,1 ntldr=/bootmgr
#

might result in the following error:

#
Insane primary (MBR) partition.
Can't find myself on the drive I booted from.
#

when using chain.c32 v4.07.

I have seen similar error reports when using chain.c32 v4.06 too.

It works correctly with chain.c32 v4.05, even when originally booting 
with SYSLINUX 4.07 (i.e. by *only* replacing chain.c32 v4.07 with the 
one from v4.05; then it works).

I don't know if chain.c32 versions newer than 4.05 are "less 
tolerant" with the partitioning scheme (or LBA/CHS?) or with the 
exact boot entry code or whether this is something else.

Is this really a bug? A regression? Other?

Is this a problem related to parsing paths? Relative paths? "/" vs. 
"\"?

Suggestions?

TIA,
Ady

PS: Just by chance, could the following commit be somehow related?
 
http://git.zytor.com/?p=syslinux/syslinux.git;a=commit;h=b82f635b7ef05
0a1c7106b213c292134aa8e6c55