Pytest 5.0 contextmanager str: call value on ExceptionInfo objects

[Ch3LL]

What does this PR do?

The tests:

unit.modules.test_localemod.LocalemodTestCase.test_gen_locale_suse_localedef_error_handling
unit.modules.test_localemod.LocalemodTestCase.test_get_locale_with_no_systemd_unknown
unit.modules.test_localemod.LocalemodTestCase.test_localectl_status_parser_broken
unit.modules.test_localemod.LocalemodTestCase.test_localectl_status_parser_empty
unit.modules.test_localemod.LocalemodTestCase.test_localectl_status_parser_no_systemd
unit.modules.test_localemod.LocalemodTestCase.test_set_locale_with_no_systemd_debian_no_update_locale
unit.modules.test_localemod.LocalemodTestCase.test_set_locale_with_no_systemd_unknown
unit.modules.test_file.FilemodLineTests.test_line_insert_ensure_beforeafter_rangelines
unit.modules.test_file.FilemodLineTests.test_line_insert_no_location_no_before_no_after
unit.modules.test_file.FilemodLineTests.test_line_modecheck_failure

are failing on mac osx because it is installing pytest 5.0.0.

This is due to the removal of __str__ here pytest-dev/pytest#5413

Updated the tests to call .value also see comment here: pytest-dev/pytest#5528 (comment)

What issues does this PR fix or reference?

Previous Behavior

tests failing:

unit.modules.test_localemod.LocalemodTestCase.test_gen_locale_suse_localedef_error_handling
unit.modules.test_localemod.LocalemodTestCase.test_get_locale_with_no_systemd_unknown
unit.modules.test_localemod.LocalemodTestCase.test_localectl_status_parser_broken
unit.modules.test_localemod.LocalemodTestCase.test_localectl_status_parser_empty
unit.modules.test_localemod.LocalemodTestCase.test_localectl_status_parser_no_systemd
unit.modules.test_localemod.LocalemodTestCase.test_set_locale_with_no_systemd_debian_no_update_locale
unit.modules.test_localemod.LocalemodTestCase.test_set_locale_with_no_systemd_unknown
unit.modules.test_file.FilemodLineTests.test_line_insert_ensure_beforeafter_rangelines
unit.modules.test_file.FilemodLineTests.test_line_insert_no_location_no_before_no_after
unit.modules.test_file.FilemodLineTests.test_line_modecheck_failure

New Behavior

test pass on pytest <=5.0.0

Tests written?

No -fixes test

Commits signed with GPG?

Yes