Perform git clone as the taiga user.

roles/taiga/tasks/main.yml

@@ -78,7 +78,13 @@
 ### DONE with db stuff
 
 ### NEXT, setup taiga-back from git
-- git: repo=https://github.com/taigaio/taiga-back.git dest=/home/taiga/taiga-back version=stable
+- command: sudo -u taiga git clone https://github.com/taigaio/taiga-back.git
+           chdir=/home/taiga/
+           creates=/home/taiga/taiga-back
+  tags: taiga
+
+- command: sudo -u taiga git checkout stable
+           chdir=/home/taiga/taiga-back
   tags: taiga
 
 - command: pip3 install -r requirements.txt