hust testsuite: fix a false positive

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/hush_test/hush-misc/assignment2.right b/shell/hush_test/hush-misc/assignment2.right
index 591552c..3812a24 100644
--- a/shell/hush_test/hush-misc/assignment2.right
+++ b/shell/hush_test/hush-misc/assignment2.right
@@ -1,2 +1,2 @@
-hush: can't exec 'a=b': No such file or directory
+hush: can't execute 'a=b': No such file or directory
 1