Constrain pexpect and ptyprocess (#73109)

The recent update of ptyprocess to 0.7.0 is incompatible with Python 2.6 and
is causing test failures.

* Add setup_pexpect role to expect test

test/integration/targets/expect/aliases

@@ -1,2 +1,3 @@
 shippable/posix/group2
 destructive
+needs/target/setup_pexpect

test/integration/targets/expect/tasks/main.yml

@@ -16,9 +16,8 @@
 # You should have received a copy of the GNU General Public License
 # along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
 - name: Install test requirements
-  pip:
-    name: pexpect
-    state: present
+  import_role:
+    name: setup_pexpect
 
 - name: record the test_command file
   set_fact: test_command_file={{output_dir | expanduser}}/test_command.py

test/integration/targets/setup_pexpect/files/constraints.txt

@@ -0,0 +1,2 @@
+pexpect == 4.8.0
+ptyprocess < 0.7.0 ; python_version < '2.7'  # ptyprocess >= 0.7.0 not compatible with Python 2.6

test/integration/targets/setup_pexpect/meta/main.yml

@@ -0,0 +1,2 @@
+dependencies:
+  - setup_remote_tmp_dir

test/integration/targets/setup_pexpect/tasks/main.yml

@@ -1,4 +1,10 @@
+- name: Copy constraints file
+  copy:
+    src: constraints.txt
+    dest: "{{ remote_tmp_dir }}/pexpect-constraints.txt"
+
 - name: Install pexpect
   pip:
     name: pexpect
+    extra_args: '--constraint "{{ remote_tmp_dir }}/pexpect-constraints.txt"'
     state: present