conflicting packages for ssreflect
The package for ssreflect in the repository confuses my installation of opam.
I am using Coq 8.6.1, and, for some reason, opam decides to use this package as the package for ssreflect and hides the official one from extra-dev. The result is that I cannot install ssreflect, since it depends on at least Coq 8.7.