surprise of the day - with

Today I was surprised by how "with" will spring a variable into existence
permanently (texmacs 2.1.2 pre-compiled deb for ubuntu focal).

What do you think this will do?

<if|<provides|dummy>|dummy exists <value|dummy>>

<with|dummy|temp-value|<if|<provides|dummy>|dummy briefly exists
<value|dummy>>>

<if|<provides|dummy>|dummy finally exists <value|dummy>>


dummy briefly exists temp-value
dummy finally exists ? <--- this line shouldn't exist

Yep - after using a <with|var|...
the var is now provided for globally -- with label uninit.

This means the <provides| test is weakened and existing macros can be
broken by other macros.

Sam