Fix coverage button

.travis.yml

@@ -12,4 +12,4 @@ os:
 
 after_success:
 - nyc npm test # 1st run fails, so force report by running nyc twice; github.com/istanbuljs/nyc/issues/993
-- nyc npm test && nyc report --reporter=text-lcov | coveralls
+- ESM_DISABLE_CACHE=1 nyc --cache=false npm test && nyc report --reporter=text-lcov | coveralls

README.md

@@ -2,7 +2,7 @@ Geodesy functions
 =================
 
 [![Build Status](https://travis-ci.org/chrisveness/geodesy.svg?branch=master)](https://travis-ci.org/chrisveness/geodesy)
-[![Coverage Status](https://coveralls.io/repos/github/chrisveness/geodesy/badge.svg?branch=master)](https://coveralls.io/github/chrisveness/geodesy?branch=master)
+[![Coverage Status](https://coveralls.io/repos/github/chrisveness/geodesy/badge.svg)](https://coveralls.io/github/chrisveness/geodesy)
 [![Documentation](https://img.shields.io/badge/docs-www.movable--type.co.uk%2Fscripts%2Fgeodesy--library.html-lightgrey.svg)](https://www.movable-type.co.uk/scripts/geodesy-library.html)
 
 These libraries started life (a long time ago) as simple ‘latitude/longitude’ code fragments