cdrtools os id when localized to cs_CZ.ISO8859-2

[Karel Rous]

    I left my localization probably at wrong state during compiling port 
of cdrtools (/usr/ports/sysutils/cdrtools) and when it was set to  
(LC_ALL=cs_CZ.ISO8859-2, LANG=cs_CZ.ISO8859-2, LANGUAGE=cs_CZ.ISO8859-2 
) then during make
it's output was like:
RULES/rules1.top:119: RULES/os-fŔÉÉbsd.id: No such file or directory
RULES/rules1.top:126: RULES/os-.def: No such file or directory
DEFAULTS/Defaults:8: DEFAULTS/Defaults.: No such file or directory
RULES/rules1.top:234: incs/Dcc.i386: No such file or directory
RULES/rules.top:39: RULES/Í386-cc.rul: No such file or directory
RULES/rules.cnf:56: incs/i386-cc/Inull: No such file or directory
RULES/rules.cnf:57: incs/i386-cc/rules.cnf: No such file or directory
p incs/i386-cc
gmake: p: Command not found
gmake: [incs/i386-cc/Inull] Error 127 (ignored)
cannot create incs/i386-cc/Inull: No such file or directory
gmake: *** [incs/i386-cc/Inull] Error 2
*** Error code 2

when set to defaults (LC_ALL=C), then everything was fine:

RULES/rules1.top:234: incs/Dcc.i386-freebsd: No such file or directory
RULES/rules.cnf:57: incs/i386-freebsd-cc/rules.cnf: No such file or 
directory
        ==> CONFIGURING RULES "incs/i386-freebsd-cc/rules.cnf"

Unfortunately I was doing many other suspicious tasks with gcc compiler 
flags that day... :)
But after all may I ask what is the possible reason for such change in 
os id?

Karel