Merge branch '197927-attaching-multiple-files-to-a-wiki-page-doesn-t-work' into 'master'

Resolve "Attaching multiple files to a wiki page doesn't work"

See merge request gitlab-org/gitlab!29029

app/assets/javascripts/dropzone_input.js

@@ -23,7 +23,7 @@ function getErrorMessage(res) {
   return res.message;
 }
 
-export default function dropzoneInput(form) {
+export default function dropzoneInput(form, config = { parallelUploads: 2 }) {
   const divHover = '<div class="div-dropzone-hover"></div>';
   const iconPaperclip = '<i class="fa fa-paperclip div-dropzone-icon"></i>';
   const $attachButton = form.find('.button-attach-file');
@@ -69,6 +69,7 @@ export default function dropzoneInput(form) {
     uploadMultiple: false,
     headers: csrf.headers,
     previewContainer: false,
+    ...config,
     processing: () => $('.div-dropzone-alert').alert('close'),
     dragover: () => {
       $mdArea.addClass('is-dropzone-hover');

app/assets/javascripts/gl_form.js

@@ -45,7 +45,7 @@ export default class GLForm {
       );
       this.autoComplete = new GfmAutoComplete(gl.GfmAutoComplete && gl.GfmAutoComplete.dataSources);
       this.autoComplete.setup(this.form.find('.js-gfm-input'), this.enableGFM);
-      dropzoneInput(this.form);
+      dropzoneInput(this.form, { parallelUploads: 1 });
       autosize(this.textarea);
     }
     // form and textarea event listeners