From 62d2df74b0c9d57fa043a29a2506381536a1226a Mon Sep 17 00:00:00 2001
From: Martin Krizek <martin.krizek@gmail.com>
Date: Fri, 20 Apr 2018 07:57:14 +0200
Subject: [PATCH] apt: fix build-dep idempotency (#38999)

---
 lib/ansible/modules/packaging/os/apt.py    |  7 ++++++-
 test/integration/targets/apt/tasks/apt.yml | 23 ++++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/lib/ansible/modules/packaging/os/apt.py b/lib/ansible/modules/packaging/os/apt.py
index 95401c38e0..2bb6712d81 100644
--- a/lib/ansible/modules/packaging/os/apt.py
+++ b/lib/ansible/modules/packaging/os/apt.py
@@ -578,7 +578,12 @@ def install(m, pkgspec, cache, upgrade=False, default_release=None,
         else:
             diff = {}
         status = True
-        data = dict(changed=True, stdout=out, stderr=err, diff=diff)
+
+        changed = True
+        if build_dep:
+            changed = APT_GET_ZERO not in out
+
+        data = dict(changed=changed, stdout=out, stderr=err, diff=diff)
         if rc:
             status = False
             data = dict(msg="'%s' failed: %s" % (cmd, err), stdout=out, stderr=err, rc=rc)
diff --git a/test/integration/targets/apt/tasks/apt.yml b/test/integration/targets/apt/tasks/apt.yml
index 0251bea489..0dd3ea36d6 100644
--- a/test/integration/targets/apt/tasks/apt.yml
+++ b/test/integration/targets/apt/tasks/apt.yml
@@ -213,3 +213,26 @@
   with_items:
     - libcaca-dev
     - libslang2-dev
+
+# https://github.com/ansible/ansible/issues/38995
+- name: build-dep for a package
+  apt:
+    name: tree
+    state: build-dep
+  register: apt_result
+
+- name: Check the result
+  assert:
+    that:
+      - apt_result is changed
+
+- name: build-dep for a package (idempotency)
+  apt:
+    name: tree
+    state: build-dep
+  register: apt_result
+
+- name: Check the result
+  assert:
+    that:
+      - apt_result is not changed