diff -up src/sage/modular/arithgroup/farey.cpp.orig src/sage/modular/arithgroup/farey.cpp --- src/sage/modular/arithgroup/farey.cpp.orig 2017-11-08 06:03:07.383885084 -0500 +++ src/sage/modular/arithgroup/farey.cpp 2017-11-08 06:03:18.271885501 -0500 @@ -136,6 +136,7 @@ operator*(const SL2Z& M, const vector