Support old version of pip installed on Travis
Support old version of pip installed on Travis
blaquee/cppformat,nelson4722/cppformat,alabuzhev/fmt,alabuzhev/fmt,wangshijin/cppformat,Jopie64/cppformat,lightslife/cppformat,wangshijin/cppformat,alabuzhev/fmt,cppformat/cppformat,dean0x7d/cppformat,cppformat/cppformat,blaquee/cppformat,wangshijin/cppformat,dean0x7d/cppformat,cppformat/cppformat,lightslife/cppformat,lightslife/cppformat,Jopie64/cppformat,blaquee/cppformat,seungrye/cppformat,seungrye/cppformat,mojoBrendan/fmt,nelson4722/cppformat,mojoBrendan/fmt,seungrye/cppformat,mojoBrendan/fmt,Jopie64/cppformat,dean0x7d/cppformat,nelson4722/cppformat