Type decorator dropped after type-maintaining value change

[philrz]

tl;dr

The loss of the type decorator =foo after this query was unexpected.

$ echo '{MyStr:"hello",MyNum:1}(=foo)' | super -c 'MyNum:=2' -
{MyStr:"hello",MyNum:2}

Details

Repro is with super commit 6e7d041.

Let's say I start with a JSUP value that has a decorator for a named record type:

$ super -version
Version: v1.18.0-189-g6e7d041f

$ echo '{MyStr:"hello",MyNum:1}(=foo)' | super -
{MyStr:"hello",MyNum:1}(=foo)

I run a query that changes a primitive value in the record without disturbing the type of that primitive value.

$ echo '{MyStr:"hello",MyNum:1}(=foo)' | super -c 'MyNum:=2' -
{MyStr:"hello",MyNum:2}

The type decorator was no longer present on the output, but I expected it would be there.

In seeking a preliminary reaction on what I observed here, @nwt agreed that the named type should probably be preserved, hence the issue.