[capabilities] fix for a newer versions of libcap (#1061) (#1110)

* [capabilities] fix for a newer versions of libcap

fixes: #993

* Minor correction for files without caps set.

PS: side note, getcap (per sources) does not set non-zero return code,
even for files which are not found (i.e. wrong filename).

* add changelog fragment

* review/suggested changes

* change comment to explicitly state stderr vs output

(cherry picked from commit 07d123a71a)

Co-authored-by: Anatoly Pugachev <matorola@gmail.com>

changelogs/fragments/993-file-capabilities.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - capabilities - fix for a newer version of libcap release (https://github.com/ansible-collections/community.general/pull/1061).

plugins/modules/system/capabilities.py

@@ -108,12 +108,18 @@ class CapabilitiesModule(object):
         #   '/foo ='
         # If file xattrs are unset the output will be:
         #   '/foo'
-        # If the file does not exist the output will be (with rc == 0...):
+        # If the file does not exist, the stderr will be (with rc == 0...):
         #   '/foo (No such file or directory)'
-        if rc != 0 or (stdout.strip() != path and stdout.count(' =') != 1):
+        if rc != 0 or stderr != "":
             self.module.fail_json(msg="Unable to get capabilities of %s" % path, stdout=stdout.strip(), stderr=stderr)
         if stdout.strip() != path:
-            caps = stdout.split(' =')[1].strip().split()
+            if ' =' in stdout:
+                # process output of an older version of libcap
+                caps = stdout.split(' =')[1].strip().split()
+            else:
+                # otherwise, we have a newer version here
+                # see original commit message of cap/v0.2.40-18-g177cd41 in libcap.git
+                caps = stdout.split()[1].strip().split()
             for cap in caps:
                 cap = cap.lower()
                 # getcap condenses capabilities with the same op/flags into a