Strange behaviour of PathChanger

[Pavel Sanda]

hi,

i have the following codes:

#1:
case LFUN_VC_COMMAND: {
        string path = cmd.getArg(1);
        support::PathChanger p(FileName(path));


#2:
case LFUN_VC_COMMAND: {
        string path = cmd.getArg(1);
        support::PathChanger p(FileName(cmd.getArg(1));


in the first case path is not changed, in the second case the path is changed.
when i put lyxerr<<"blabla" into the constructor of pathchanger the message
is showed only in the second case.

i hope i'm too much tired and missing something obvious because the compiler
shouldn't "optimalize" this code (p is not used anywhere else in the block).

please can somebody with fresh eyes look what i'm doing wrong?
pavel