From d6e711b1dedf5908bdae25d3e9496a241d0e49d4 Mon Sep 17 00:00:00 2001
From: Robin Roth <robin@rroth.de>
Date: Mon, 14 May 2018 14:51:10 +0200
Subject: [PATCH] Allow empty list of names in pip module (#38789)

pip 10 gives exit code 1 for empty argument lists (pip < 10 gave exit 0)
see also https://github.com/pypa/pip/pull/4210

To still allow playbooks to pass when giving empty lists, don't call
pip in that case, but show a warning.
---
 lib/ansible/modules/packaging/language/pip.py |  8 ++++++--
 test/integration/targets/pip/tasks/pip.yml    | 11 +++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/lib/ansible/modules/packaging/language/pip.py b/lib/ansible/modules/packaging/language/pip.py
index 83ee128c29..19665e8f13 100644
--- a/lib/ansible/modules/packaging/language/pip.py
+++ b/lib/ansible/modules/packaging/language/pip.py
@@ -496,9 +496,13 @@ def main():
         if name:
             for pkg in name:
                 cmd += ' %s' % _get_full_name(pkg, version)
+        elif requirements:
+            cmd += ' -r %s' % requirements
         else:
-            if requirements:
-                cmd += ' -r %s' % requirements
+            module.exit_json(
+                changed=False,
+                warnings=["No valid name or requirements file found."],
+            )
 
         if module.check_mode:
             if extra_args or requirements or state == 'latest' or not name:
diff --git a/test/integration/targets/pip/tasks/pip.yml b/test/integration/targets/pip/tasks/pip.yml
index 25c70bf6b3..be46a28ad6 100644
--- a/test/integration/targets/pip/tasks/pip.yml
+++ b/test/integration/targets/pip/tasks/pip.yml
@@ -208,3 +208,14 @@
   assert:
     that:
       - "venv_chdir.changed"
+
+# ansible#38785
+- name: allow empty list of packages
+  pip:
+    name: []
+  register: pip_install_empty
+
+- name: ensure empty install is successful
+  assert:
+    that:
+      - not pip_install_empty.changed