hush: fix "$v" expansion in case patterns when v='[a]'

function                                             old     new   delta
run_list                                            1053    1063     +10
setup_redirects                                      311     320      +9
encode_then_expand_string                            135     142      +7
run_pipe                                            1784    1789      +5
expand_assignments                                    81      86      +5
expand_string_to_string                              124     125      +1
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(add/remove: 0/0 grow/shrink: 6/0 up/down: 37/0)               Total: 37 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/ash_test/ash-quoting/case_glob1.tests b/shell/ash_test/ash-quoting/case_glob1.tests
new file mode 100755
index 0000000..8dbbc0f
--- /dev/null
+++ b/shell/ash_test/ash-quoting/case_glob1.tests
@@ -0,0 +1,8 @@
+g='[3](a)(b)(c)'
+s='[3](a)(b)(c)'
+case $g in
+"$s")   echo s
+        ;;
+*)      echo "*"
+        ;;
+esac