template.to_yaml(clean_up=True) produces invalid template

it replaces valid template input

Value:
Fn::Join:
- ","
- - Fn::If:
- HasZoneA
- Ref: PublicSubnetA
- Ref: "AWS::NoValue"
- Fn::If:
- HasZoneB
- Ref: PublicSubnetB
- Ref: "AWS::NoValue"
- Fn::If:
- HasZoneC
- Ref: PublicSubnetC
- Ref: "AWS::NoValue"

by

Value: !Sub
- ${Param1},${Param2},${Param3}
- Param1: !If
- HasZoneA
- !Ref 'PublicSubnetA'
- !Ref 'AWS::NoValue'
Param2: !If
- HasZoneB
- !Ref 'PublicSubnetB'
- !Ref 'AWS::NoValue'
Param3: !If
- HasZoneC
- !Ref 'PublicSubnetC'
- !Ref 'AWS::NoValue'

and then fails

_Originally posted by @christianbeland in https://github.com/cloudtools/troposphere/issues/976#issuecomment-468007634_