Fixed the blob editor deleting all content for files

This only happens for files that the path consists of only numbers

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/58578

app/assets/javascripts/blob_edit/blob_bundle.js

@@ -13,7 +13,7 @@ export default () => {
   if (editBlobForm.length) {
     const urlRoot = editBlobForm.data('relativeUrlRoot');
     const assetsPath = editBlobForm.data('assetsPrefix');
-    const filePath = editBlobForm.data('blobFilename');
+    const filePath = `${editBlobForm.data('blobFilename')}`;
     const currentAction = $('.js-file-title').data('currentAction');
     const projectId = editBlobForm.data('project-id');
     const isMarkdown = editBlobForm.data('is-markdown');

changelogs/unreleased/fix-blob-editor-deleting-content.yml

+---
+title: Fixed blob editor deleting file content for certain file paths
+merge_request:
+author:
+type: fixed

spec/features/projects/blobs/edit_spec.rb

@@ -49,6 +49,15 @@ describe 'Editing file blob', :js do
       end
     end
 
+    it 'updates the content of file with a number as file path' do
+      project.repository.create_file(user, '1', 'test', message: 'testing', branch_name: branch)
+      visit project_blob_path(project, tree_join(branch, '1'))
+
+      edit_and_commit
+
+      expect(page).to have_content 'NextFeature'
+    end
+
     context 'from blob file path' do
       before do
         visit project_blob_path(project, tree_join(branch, file_path))