pools are then used only to fetch new conenctions; selectors are discarded when not needed anymore; HTTPX.wrap is for now patched, but would ideally be done with in the future
Some requests were hanging because some connection with read interests
were only on the writers selector. This issue manifested itself in high
load scenarios.
The fix is not the most performant, but it does the job: only set write
interest when connecting, otherwise read/write. This increases the
number of wakeups, but at least we have correctness.
