* Revert "Account for empty string regexp in lineinfile (#41451)"
This reverts commit 4b5b4a760c.
* Use context managers for interacting with files
* Store line and regexp parameters in a variable
* Add warning when regexp is an empty string
* Remove '=' from error messages
* Update warning message and add changelog
* Add tests
* Improve warning message
Offer an equivalent regexp that won't trigger the warning.
Update tests to match new warning.
* Add porting guide entry for lineinfile change
(cherry picked from commit fb55038d75)
* Skip if insertbefore BOF until later (#41767)
If a line match is found in the file and no regexp is specified, insertbefore would improperly try to add a line if set to BOF.
Add tests for this scenario.
(cherry picked from commit eaae1318f8)
* Add changelog fragment
* Insert lines before or after when the regexp exists elsewhere in the file
* Correct filter syntax in lineinfile integration test
* Use multi-line YAML syntax on lineinfile tests
Unify indentation
* Add lineinfile tests for same line matched to different regexps
* Remove debug statement from test
