Fix environment passung to eval'ed commands.

PR:		bin/6577
Submitted by:	Anatoly Vorobey <mellon@pobox.com>
Approved by:	silence amoung other sh experts

bin/sh/eval.c

@@ -850,6 +850,7 @@ evalcommand(cmd, flags, backcmd)
 		exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
 		flushall();
 cmddone:
+		cmdenviron = NULL;
 		out1 = &output;
 		out2 = &errout;
 		freestdout();

bin/sh/expand.c

@@ -667,7 +667,7 @@ evalvar(p, flag)
 		set = varisset(var, varflags & VSNUL);
 		val = NULL;
 	} else {
-		val = lookupvar(var);
+		val = bltinlookup(var, 1);
 		if (val == NULL || ((varflags & VSNUL) && val[0] == '\0')) {
 			val = NULL;
 			set = 0;