fix opam repo ranks

prepare-opam.sh

@@ -32,18 +32,20 @@ else
 fi
 eval `opam conf env`
 
-# Make sure we got the right set of repositories registered
+# Make sure we got the right set of repositories registered.
+# By default, they are added with rank 1, i.e. at the top of the list. So we add them with increasing priority.
+test -d "$OPAMROOT/repo/coq-released" || opam repo add coq-released https://coq.inria.fr/opam/released
 if echo "$@" | egrep "(dev|beta)" > /dev/null; then
     # We are compiling against a dev version of something.  Get ourselves the dev repositories.
-    test -d "$OPAMROOT/repo/coq-extra-dev" || opam repo add coq-extra-dev https://coq.inria.fr/opam/extra-dev --rank 0
-    test -d "$OPAMROOT/repo/coq-core-dev" || opam repo add coq-core-dev https://coq.inria.fr/opam/core-dev --rank 5
+    test -d "$OPAMROOT/repo/coq-extra-dev" || opam repo add coq-extra-dev https://coq.inria.fr/opam/extra-dev
+    test -d "$OPAMROOT/repo/coq-core-dev" || opam repo add coq-core-dev https://coq.inria.fr/opam/core-dev
 else
     # No dev version, make sure we do not have the dev repositories.
     test -d "$OPAMROOT/repo/coq-extra-dev" && opam repo remove coq-extra-dev
     test -d "$OPAMROOT/repo/coq-core-dev" && opam repo remove coq-core-dev
 fi
-test -d "$OPAMROOT/repo/coq-released" || opam repo add coq-released https://coq.inria.fr/opam/released --rank 10
-test -d "$OPAMROOT/repo/iris-dev" || opam repo add iris-dev https://gitlab.mpi-sws.org/FP/opam-dev.git --rank 20
+test -d "$OPAMROOT/repo/iris-dev" || opam repo add iris-dev https://gitlab.mpi-sws.org/FP/opam-dev.git
+opam repo prio iris-dev 1 # make sure this stays at the top
 echo
 
 # Make sure the the builddep package exists and is up-to-date.