tweak COQTEST output

Makefile.coq.local

@@ -23,12 +23,11 @@ $(TESTFILES:.v=.vo): %.vo: %.v $(if $(MAKE_REF),,%.ref)
 	  else \
 	    REF="tests/$$TEST.ref"; \
 	  fi && \
-	  echo "COQTEST$(if $(MAKE_REF), [make ref],$(if $(COQ_OLD), [no ref],)) $$REF" && \
+	  echo "COQTEST$(if $(COQ_OLD), [no ref],$(if $(MAKE_REF), [make ref],)) $<$(if $(COQ_OLD),, (ref: $$REF))" && \
 	  TMPFILE="$$(mktemp)" && \
 	  $(TIMER) $(COQ_TEST) $(COQFLAGS) $(COQLIBS) -load-vernac-source $< > "$$TMPFILE" && \
-	  $(if $(MAKE_REF), \
-	    mv "$$TMPFILE" "$$REF", \
-	    $(if $(COQ_OLD),true,diff -u "$$REF" "$$TMPFILE") \
+	  $(if $(COQ_OLD),true, \
+	    $(if $(MAKE_REF),mv "$$TMPFILE" "$$REF",diff -u "$$REF" "$$TMPFILE") \
 	  ) && \
 	  rm -f "$$TMPFILE" && \
 	  touch $@