ash: parser: Only accept single-digit parameter expansion outside of braces

Upstream commit:

    Date: Mon, 27 May 2019 13:39:37 +0800
    parser: Only accept single-digit parameter expansion outside of braces

    This patch should fix the problem.

    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/hush_test/hush-vars/var_10.right b/shell/hush_test/hush-vars/var_10.right
new file mode 100644
index 0000000..675ab45
--- /dev/null
+++ b/shell/hush_test/hush-vars/var_10.right
@@ -0,0 +1,3 @@
+Zero:0
+One:1
+Done:0
diff --git a/shell/hush_test/hush-vars/var_10.tests b/shell/hush_test/hush-vars/var_10.tests
new file mode 100755
index 0000000..7364efb
--- /dev/null
+++ b/shell/hush_test/hush-vars/var_10.tests
@@ -0,0 +1,4 @@
+set -- : 2 3 4 5 6 7 8 9 ten eleven
+echo Zero$10
+echo One$11
+echo Done:$?