hush: fix handling of } which is not a closing one in { cmd; }

function                                             old     new   delta
parse_stream                                        2176    2302    +126
builtin_unset                                        381     387      +6

diff --git a/shell/hush_test/hush-vars/var_posix1.right b/shell/hush_test/hush-vars/var_posix1.right
index 373b16c..47d52a6 100644
--- a/shell/hush_test/hush-vars/var_posix1.right
+++ b/shell/hush_test/hush-vars/var_posix1.right
@@ -22,6 +22,7 @@
 babcdcd
 ababcdcd
 Empty:
+ababcdcd}_tail
 ababcd
 ababcd
 ababcd
@@ -30,4 +31,5 @@
 ababcdc
 ababcdcd
 Empty:
+ababcdcd}_tail
 end
diff --git a/shell/hush_test/hush-vars/var_posix1.tests b/shell/hush_test/hush-vars/var_posix1.tests
index 0ce531d..3069360 100755
--- a/shell/hush_test/hush-vars/var_posix1.tests
+++ b/shell/hush_test/hush-vars/var_posix1.tests
@@ -30,6 +30,8 @@
 echo ${var##?}
 echo ${var#*}
 echo Empty:${var##*}
+echo ${var#}}_tail
+# UNFIXED BUG: echo ${var#\}}_tail
 
 echo ${var%cd}
 echo ${var%%cd}
@@ -39,5 +41,7 @@
 echo ${var%%?}
 echo ${var%*}
 echo Empty:${var%%*}
+echo ${var#}}_tail
+# UNFIXED BUG: echo ${var#\}}_tail
 
 echo end