httppeer: avoid large dumps when we don't see an hgweb repo
When we don't get an hgweb protocol response, we dump the response to
the user for diagnostic purposes (it might be a cgitb message, for
instance).
But if we try to clone a bundle, we don't want to show the
entire bundle in the error message. Also, we don't want fetch the
full bundle multiple times during fallback. So we only fetch 1k here.
$ hg init t
$ cd t
$ echo a > a
$ hg add a
$ hg commit -m test
$ rm .hg/requires
$ hg tip
abort: index 00changelog.i unknown format 2!
[255]
$ echo indoor-pool > .hg/requires
$ hg tip
abort: unknown repository format: requires features 'indoor-pool' (upgrade Mercurial)!
[255]
$ echo outdoor-pool >> .hg/requires
$ hg tip
abort: unknown repository format: requires features 'indoor-pool', 'outdoor-pool' (upgrade Mercurial)!
[255]
$ cd ..