silence bootstrap 'error' on unalias of undefined alias

bootstrap.1

@@ -8,10 +8,10 @@ if test -z "${SOLARENV}"; then
 fi
 
 # remove aliases set by Env.Host.sh
-unalias mkout
-unalias deliver
-unalias build
-unalias zipdep
+unalias mkout    2> /dev/null
+unalias deliver  2> /dev/null
+unalias build    2> /dev/null
+unalias zipdep   2> /dev/null
 
 # executables are *.exe for WNT. This variable is necessary since Cygwin 1.5.x
 # Use spawn instead of fork when building dmake on cygwin.