There are a few places in core that were preventing this from working by explicity setting `$wpdb->suppress_errors` to `false`. Instead, they should inherit the value that existed before errors were suppressed.
This allows Multisite unit tests to run without explosive database errors, and allows `$wpdb->suppress_errors` to be overridden all the way down the chain.
Fixes#26102.
git-svn-id: https://develop.svn.wordpress.org/trunk@26252 602fd350-edb4-49c9-b593-d223f7449a82