Add integration tests for 'modules.file.replace()'.
Fix backup and pre-/append behaviour in modules.file.replace():
Simplify initial search. Determine 'backup' properly.
Add missing line.
Fix tests for #18841.
Fix tests for #18841.
Pylint.
Merge pull request #19047 from eliasp/2014.7-modules.file.replace-test-coverage

2014.7 file.replace integration test coverage