Remove one false positive on pipe-fail rule

Avoid triggering the rule if pipefail string is used anywhere inside
the script instead of only the first line. We can assume user knew
what to do if it used it.

Fixes: #663

src/ansiblelint/rules/ShellWithoutPipefail.py

@@ -20,7 +20,7 @@ class ShellWithoutPipefail(AnsibleLintRule):
     tags = ['command-shell']
     version_added = 'v4.1.0'
 
-    _pipefail_re = re.compile(r"^\s*set.*[+-][A-z]*o\s*pipefail")
+    _pipefail_re = re.compile(r"^\s*set.*[+-][A-z]*o\s*pipefail", re.M)
     _pipe_re = re.compile(r"(?<!\|)\|(?!\|)")
 
     def matchtask(self, task: Dict[str, Any]) -> Union[bool, str]:
@@ -39,6 +39,6 @@ def matchtask(self, task: Dict[str, Any]) -> Union[bool, str]:
 
         return bool(
             self._pipe_re.search(unjinjad_cmd)
-            and not self._pipefail_re.match(unjinjad_cmd)
+            and not self._pipefail_re.search(unjinjad_cmd)
             and not convert_to_boolean(task['action'].get('ignore_errors', False))
         )

test/TestShellWithoutPipefail.py

@@ -48,6 +48,12 @@
         set -eo pipefail
         false | cat
 
+    - name: pipeline with pipefail not at first line
+      shell: |
+        echo foo
+        set -eo pipefail
+        false | cat
+
     - name: pipeline without pipefail, ignoring errors
       shell: false | cat
       ignore_errors: true