Two concurrent fetches can occur from the same peer, while also being
for a different set of references. This was seen in the
`test_outdated_sigrefs` test. Alice would have an ongoing fetch from
Eve, and concurrently, Eve will create a new issue -- thus creating a
new `RefsAt` message -- and Alice would attempt to fetch this.
The previous logic would only check that Alice is fetching from Eve
and ignore the new updates -- meaning the test could fail. However, if
the `RefsAt` are checked then the other fetch can be recognised as
new, and queue it.
Signed-off-by: Fintan Halpenny <fintan.halpenny@gmail.com>
X-Clacks-Overhead: GNU Terry Pratchett
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