hush: fix comment parsing in `cmd`, closes 10421

function                                             old     new   delta
parse_stream                                        2692    2690      -2

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/hush_test/hush-parsing/comment2.tests b/shell/hush_test/hush-parsing/comment2.tests
new file mode 100755
index 0000000..b7adad9
--- /dev/null
+++ b/shell/hush_test/hush-parsing/comment2.tests
@@ -0,0 +1,13 @@
+echo "`echo Ok1 #comment is ignored`"
+echo `echo Ok2 #comment is ignored`
+#
+# Surprisingly, bash does not handle comments in $()
+# the same way as in ``. "#" causes the rest of the line, _including_ )",
+# to be ignored. These lines would cause an error:
+#echo "$(echo Ok3 #comment is ignored)"
+#echo $(echo Ok4 #comment is ignored)
+#
+echo "$(echo Ok5 #comment is ignored
+)"
+echo $(echo Ok6 #comment is ignored
+)