I don't think this problem is really serious. If the push fails, you can just commit (locally) a new changeset that repairs the EOL or indentation problems
I would find that unfortunate. It's a fairly irrelevant change, yet it may manage to corrupt the history (hg blame).
and push the whole bunch of changesets again (I assume the server-side hook will not examine changesets individually, but only the last of them?).
That is for us to decide. I can see arguments either way.
But it shouldn't happen often that the server refuses a push; all errors should already be caught on the clients.