Ensure git clones discard local modifications

If a cloned repo contains local modifications, the clone task will
fail. This ensures any local modifications are discarded, ensuring a
successful clone.

Change-Id: Ic5799fe07e15739cc11acabba803e3be47606f94
Closes-Bug: #1506590

playbooks/roles/os_nova/tasks/nova_console_novnc_install.yml

@@ -20,6 +20,7 @@
     clone: "yes"
     update: "yes"
     version: "{{ nova_novncproxy_git_install_branch }}"
+    force: yes
   register: git_clone
   until: git_clone|success
   retries: 5

playbooks/roles/os_nova/tasks/nova_console_spice_install.yml

@@ -45,6 +45,7 @@
     clone: "yes"
     update: "yes"
     version: "{{ nova_spicehtml5_git_install_branch }}"
+    force: yes
   register: git_clone
   until: git_clone|success
   retries: 5

playbooks/roles/os_tempest/tasks/tempest_install.yml

@@ -33,6 +33,7 @@
     repo: "{{ tempest_git_repo }}"
     dest: "{{ tempest_git_dest }}"
     version: "{{ tempest_git_install_branch }}"
+    force: yes
   register: git_clone
   until: git_clone|success
   retries: 5

playbooks/roles/py_from_git/tasks/main.yml

@@ -18,6 +18,7 @@
     repo: "{{ git_repo }}"
     dest: "{{ git_dest }}"
     version: "{{ git_install_branch }}"
+    force: yes
   register: git_clone
   until: git_clone|success
   retries: 5