It would be fairly easy for somebody to get confused in masquerade mode and try to get distcc to invoke itself in a loop. We can't always work out the right thing to do but we can at least flag an error.
This environment variable is set to guard against distcc accidentally recursively invoking itself, thinking it's the real compiler.
Definition in file safeguard.cpp.
|static const char||dcc_safeguard_name  = "_ICECREAM_SAFEGUARD"|
|static char||dcc_safeguard_set  = "_ICECREAM_SAFEGUARD=1"|