minor bug fix for graph export (for nodes without label)
minor bug fix for graph export (for nodes without label)

pombredanne/pattern,shuangsong/pattern,elkingtonmcb/pattern,shubhangiKishore/pattern,EricSchles/pattern,z0by/pattern,rebeling/pattern,woiddei/pattern,pattern3/pattern,soycode/pattern,ashhher3/pattern,hayd/pattern,dongguangming/pattern,hayd/pattern,codeaudit/pattern-1,Sri0405/pattern,soycode/pattern,sfprime/pattern,Sri0405/pattern,RitwikGupta/pattern,aoom/pattern,abcht/pattern,bijandhakal/pattern,piskvorky/pattern,pombredanne/pattern,dongguangming/pattern,piskvorky/pattern,clips/pattern,woiddei/pattern,pattern3/pattern,dongguangming/pattern,Sri0405/pattern,codeaudit/pattern-1,rebeling/pattern,woiddei/pattern,bijandhakal/pattern,z0by/pattern,pombredanne/pattern,jatinmistry13/pattern,elkingtonmcb/pattern,jatinmistry13/pattern,EricSchles/pattern,clips/pattern,aoom/pattern,pattern3/pattern,RitwikGupta/pattern,sfprime/pattern,textioHQ/pattern,jatinmistry13/pattern,arne-cl/pattern,bijandhakal/pattern,aoom/pattern,hayd/pattern,rebeling/pattern,EricSchles/pattern,ashhher3/pattern,ashhher3/pattern,codeaudit/pattern-1,abcht/pattern,z0by/pattern,abcht/pattern,shuangsong/pattern,shuangsong/pattern,loretoparisi/pattern,shubhangiKishore/pattern,bijandhakal/pattern,dongguangming/pattern,abcht/pattern,jatinmistry13/pattern,clips/pattern,NTesla/pattern,arne-cl/pattern,sfprime/pattern,RitwikGupta/pattern,soycode/pattern,Sri0405/pattern,arne-cl/pattern,EricSchles/pattern,codeaudit/pattern-1,loretoparisi/pattern,NTesla/pattern,NTesla/pattern,elkingtonmcb/pattern,arne-cl/pattern,pombredanne/pattern,loretoparisi/pattern,loretoparisi/pattern,shubhangiKishore/pattern,ashhher3/pattern,woiddei/pattern,RitwikGupta/pattern,z0by/pattern,piskvorky/pattern,rebeling/pattern,elkingtonmcb/pattern,sfprime/pattern,shuangsong/pattern,NTesla/pattern,soycode/pattern,aoom/pattern