This patch optimizes how the issues are collected.
Before, the issues where pushed to a new instance of `Vec`, which was
not preallocated to the size of the iterator.
This could be slow when a large number of issues is returned by the
iterator.
With the `Iterator::collect` function, the `FromIterator` implementation
of `Vec` is used, which makes use of `Iterator::size_hint` for
optimizing how much space is preallocated when collecting into the
`Vec`.
Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
f6f3be437b