Use current git branch by default when setting up cypress container

Signed-off-by: Louis Chemineau <louis@chmn.me>

cypress/dockerNode.ts

 import Docker from 'dockerode'
 import waitOn from 'wait-on'
 import tar from 'tar'
+import { execSync } from 'child_process'
 
 export const docker = new Docker()
 
  *
  * @param {string} branch the branch of your current work
  */
-export const startNextcloud = async function(branch = 'master'): Promise<any> {
+export const startNextcloud = async function(branch: string = getCurrentGitBranch()): Promise<any> {
 
 	try {
 		// Pulling images
 const sleep = function(milliseconds: number) {
 	return new Promise((resolve) => setTimeout(resolve, milliseconds))
 }
+
+const getCurrentGitBranch = function() {
+	return execSync('git rev-parse --abbrev-ref HEAD').toString().trim() || 'master'
+}