Fixing #184 Content type removed if data is false

lib/adapters/xhr.js

@@ -82,7 +82,7 @@ module.exports = function xhrAdapter(resolve, reject, config) {
   // Add headers to the request
   if ('setRequestHeader' in request) {
     utils.forEach(requestHeaders, function setRequestHeader(val, key) {
-      if (!requestData && key.toLowerCase() === 'content-type') {
+      if ((requestData === undefined || requestData === null) && key.toLowerCase() === 'content-type') {
         // Remove Content-Type if data is undefined
         delete requestHeaders[key];
       } else {

test/specs/headers.spec.js

@@ -99,7 +99,7 @@ describe('headers', function () {
     }, 0);
   });
 
-  xit('should preserve content-type if data is false', function (done) {
+  it('should preserve content-type if data is false', function (done) {
     axios({
       url: '/foo',
       method: 'post',