Try optimistic chown, do not error out if not permitted to chown

Add unit test

lib/ansible/module_utils/basic.py

@@ -1145,9 +1145,13 @@ class AnsibleModule(object):
                 if self.selinux_enabled():
                     self.set_context_if_different(
                         tmp_dest.name, context, False)
-                tmp_stat = os.stat(tmp_dest.name)
+		try:
-                if dest_stat and (tmp_stat.st_uid != dest_stat.st_uid or tmp_stat.st_gid != dest_stat.st_gid) and os.getuid() == 0:
+		    tmp_stat = os.stat(tmp_dest.name)
-                    os.chown(tmp_dest.name, dest_stat.st_uid, dest_stat.st_gid)
+		    if dest_stat and (tmp_stat.st_uid != dest_stat.st_uid or tmp_stat.st_gid != dest_stat.st_gid):
+			os.chown(tmp_dest.name, dest_stat.st_uid, dest_stat.st_gid)
+		except OSError, e:
+		    if e.errno != errno.EPERM:
+			raise
                 os.rename(tmp_dest.name, dest)
             except (shutil.Error, OSError, IOError), e:
                 self.cleanup(tmp_dest.name)

test/integration/roles/test_copy/tasks/main.yml

@@ -180,3 +180,28 @@
       - "copy_result6.changed"
       - "copy_result6.dest == '{{output_dir|expanduser}}/multiline.txt'"
       - "copy_result6.md5sum == '1627d51e7e607c92cf1a502bf0c6cce3'"
+
+# test overwriting a file as an unprivileged user (pull request #8624)
+# this can't be relative to {{output_dir}} as ~root usually has mode 700
+
+- name: create world writable directory
+  file: dest=/tmp/worldwritable state=directory mode=0777
+
+- name: create world writable file
+  copy: dest=/tmp/worldwritable/file.txt content="bar" mode=0666
+
+- name: overwrite the file as user nobody
+  copy: dest=/tmp/worldwritable/file.txt content="baz"
+  sudo: yes
+  sudo_user: nobody
+  register: copy_result7
+
+- name: assert the file was overwritten
+  assert:
+    that:
+      - "copy_result7.changed"
+      - "copy_result7.dest == '/tmp/worldwritable/file.txt'"
+      - "copy_result7.md5sum == '73feffa4b7f6bb68e44cf984c85f6e88'"
+
+- name: clean up
+  file: dest=/tmp/worldwritable state=absent