fix: Avoid premature release for external pointers

[krlmlr]

trafficstars

From duckdb, see #401.

This is fairly severe.

[pachadotdev]

From duckdb, see #401.

This is fairly severe.

I found the same while porting magick

[krlmlr]

@copilot: Add a test based on the linked issue #308.

[krlmlr]

I imagine that this would need a test. Copilot does not talk to me today, but I remember testing with the motivating example in #308, and the vendored and patched version of cpp11 works just fine for me.

[pachadotdev]

I imagine that this would need a test. Copilot does not talk to me today, but I remember testing with the motivating example in #308, and the vendored and patched version of cpp11 works just fine for me.

hi! I ended up creating cpp4r to add some corrections/features that are out scope based on the last email from Hadley

[pachadotdev]

I imagine that this would need a test. Copilot does not talk to me today, but I remember testing with the motivating example in #308, and the vendored and patched version of cpp11 works just fine for me.

and you can vendor to src, I tagged you here https://github.com/pachadotdev/cpp4r/commit/11afe2fa4e453b627c8767e53edd0e67e1098a81