CI: let's see if opam reinstall works faster than opam upgrade for changing build-deps

Makefile

@@ -20,7 +20,7 @@ Makefile.coq: _CoqProject Makefile awk.Makefile
 
 # Install build-dependencies
 build-dep/opam: opam Makefile
-	# Creating the build-dep package.
+	@echo "# Creating build-dep package."
 	@mkdir -p build-dep
 	@sed <opam -E 's/^(build|install|remove):.*/\1: []/; s/^name: *"(.*)" */name: "\1-builddep"/' >build-dep/opam
 	@fgrep builddep build-dep/opam >/dev/null || (echo "sed failed to fix the package name" && exit 1) # sanity check
@@ -31,12 +31,13 @@ build-dep: build-dep/opam phony
 	@# that are incompatible with our build requirements.
 	@# To achieve this, we create a fake opam package that has our build-dependencies as
 	@# dependencies, but does not actually install anything.
-	@# Upgrading is needed in case the pin already exists, but the builddep package changed.
+	@# Reinstalling is needed in case the pin already exists, but the builddep package changed.
+	@# Once we depend on opam 2, we can remove that last step.
 	@BUILD_DEP_PACKAGE="$$(egrep "^name:" build-dep/opam | sed 's/^name: *"\(.*\)" */\1/')"; \
 	  echo "# Pinning build-dep package." && \
 	  opam pin add -k path $(OPAMFLAGS) "$$BUILD_DEP_PACKAGE".dev build-dep && \
-	  echo "# Updating build-dep package." && \
-	  opam upgrade "$$BUILD_DEP_PACKAGE"
+	  echo "# Reinstalling build-dep package." && \
+	  opam reinstall $(OPAMFLAGS) "$$BUILD_DEP_PACKAGE"
 
 # Some files that do *not* need to be forwarded to Makefile.coq
 Makefile: ;

ci @ 40b71102

-Subproject commit 9028d6c194dff126443a1d19f23a13ac1e8ead3a
+Subproject commit 40b71102efe051c777a785035aebcbaa4c2ec19f