clicking on a package in package-list-packages pops down an open package detail view

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Steps to reproduce:

1. M-x package-list-packages (following my instructions to not get pwnt first, of course)
2. click on a package; notice that the package detail help buffer pops up nicely
3. click on another package.

observed behavior:

the package detail buffer disappears!

expected behavior:

Instead, the package detail buffer should stick around but get updated with the new package details.

Thanks for popwin!