Just nuke environ instead of trying to unsetenv everything because that

doesn't necessarily work if there is an entry with an empty name.

environ.c

@@ -196,18 +196,10 @@ void
 environ_push(struct environ *env)
 {
 	struct environ_entry	*envent;
-	char			*v;
-
-	while (*environ != NULL) {
-		v = xstrdup(*environ);
-		v[strcspn(v, "=")] = '\0';
-
-		unsetenv(v);
-		free(v);
-	}
 
+	environ = xcalloc(1, sizeof *environ);
 	RB_FOREACH(envent, environ, env) {
-		if (envent->value != NULL)
+		if (envent->value != NULL && *envent->name != '\0')
 			setenv(envent->name, envent->value, 1);
 	}
 }