Fixes #16363 - fix taxable user deletion

[ares]

Reproducing steps:

as admin:

1. create a user and assign him some organization
2. create user group and assign this new user to this user group
3. switch context to this org, do not remain in Any Context where all works
4. try deleting the user
5. see the error

with this fix, the user gets deleted

technical details:
belongs_to respects the default scope which unfortunately is used by taxonomies, therefore when member is being loaded, it fails resulting in member being nil. When it's later passed to find_all_affected_users_for, it fails since nil is unknown member type. In this case we need to skip taxonomies verification. Sadly we can't use any of common tricks since this is a polymorphic associations.

belongs_to :member, -> { unscope(:where) }, :polymorphic => true does not work since it also reset the where defined by polymorphic part, taxonomix does not define any named scope, just where("id IN ...")

[theforeman-bot]

Issues: #16363

[mmoll]

alias_method_chain will be gone in Rails 5.1, see 3896497

[tstrachota]

👍 for both the code and functionality. I tested the patch today and it works nicely.

[timogoebel]

@ares: Looks good, just one small comment.

[timogoebel]

... Foreman::Exception.new() ?

[tstrachota]

Good catch. We raise it as ArgumentError on two other locations in this file. Whatever exception type we use, we should be consistent.

[ares]

I agree, I changed the exception to ArgumentError since this is an internal exception for devs, not really for users.

[houndci-bot]

Some files could not be reviewed due to errors:

.rubocop.yml: Style/FileName has the wrong namespace - should be Naming

.rubocop.yml: Style/FileName has the wrong namespace - should be Naming
.rubocop.yml: Style/PredicateName has the wrong namespace - should be Naming
.rubocop.yml: Style/AccessorMethodName has the wrong namespace - should be Naming
.rubocop.yml: Style/MethodName has the wrong namespace - should be Naming
.rubocop.yml: Style/VariableNumber has the wrong namespace - should be Naming
Error: The `Style/OpMethod` cop has been renamed and moved to `Naming/BinaryOperatorParameterName`.
(obsolete configuration found in .rubocop.yml, please update it)

[timogoebel]

@ares: Can you rebase please to fix the test failures? Thanks.

[ares]

rebased

[mmoll]

test failures related ;)

[ares]

ah I accidentally pushed older version from a different computer, should be good now

[timogoebel]

@ares: Before I merge this, one final question, just to make sure: Is there a case when member_type might be nil?

[ares]

no, I'm not aware such case, it's always user or user group

[timogoebel]

Merged, thanks @ares and @tstrachota.

I'll put this on 1.17, but feel free to put it in 1.16 at your own discretion.

[ares]

Thanks, I think it's fine to keep for 1.17, it's not 1.16 regression.