fix(cli): Make gz -a working again (#573)

closes #543

Author: thierrymichel

src/commitizen/staging.js

@@ -6,7 +6,7 @@ export { isClean };
  * Asynchrounously determines if the staging area is clean
  */
 function isClean (repoPath, done) {
-  exec('git diff --cached --name-only', {
+  exec('git diff --no-ext-diff --name-only && git diff --no-ext-diff --cached --name-only', {
     maxBuffer: Infinity,
     cwd: repoPath || process.cwd()
   }, function (error, stdout) {

test/tests/staging.js

@@ -63,9 +63,20 @@ describe('staging', function () {
         staging.isClean(repoConfig.path, function (afterWriteStagingIsCleanError, afterWriteStagingIsClean) {
           expect(afterWriteStagingIsCleanError).to.be.null;
           expect(afterWriteStagingIsClean).to.be.false;
-          done();
-        });
 
+          writeFilesToPath({
+            dummymodified: {
+              contents: repoConfig.files.dummyfile.contents + '-modified',
+              filename: repoConfig.files.dummyfile.filename,
+            }
+          }, repoConfig.path);
+
+          staging.isClean(repoConfig.path, function (afterWriteStagingIsCleanError, afterWriteStagingIsClean) {
+            expect(afterWriteStagingIsCleanError).to.be.null;
+            expect(afterWriteStagingIsClean).to.be.false;
+            done();
+          });
+        });
       });
     });
   });