Support old version of pip installed on Travis, take 2
Support old version of pip installed on Travis, take 2
Jopie64/cppformat,lightslife/cppformat,alabuzhev/fmt,Jopie64/cppformat,dean0x7d/cppformat,lightslife/cppformat,blaquee/cppformat,mojoBrendan/fmt,cppformat/cppformat,mojoBrendan/fmt,alabuzhev/fmt,cppformat/cppformat,Jopie64/cppformat,wangshijin/cppformat,blaquee/cppformat,dean0x7d/cppformat,seungrye/cppformat,wangshijin/cppformat,lightslife/cppformat,seungrye/cppformat,dean0x7d/cppformat,nelson4722/cppformat,nelson4722/cppformat,wangshijin/cppformat,blaquee/cppformat,mojoBrendan/fmt,cppformat/cppformat,nelson4722/cppformat,seungrye/cppformat,alabuzhev/fmt