Minor bug fix for removing identical children from a non-deterministich node.
Minor bug fix for removing identical children from a non-deterministich node.

hjwylde/whiley-compiler,Whiley/WhileyCompiler,hjwylde/whiley-compiler,hjwylde/whiley-compiler,hjwylde/whiley-compiler,hjwylde/whiley-compiler