I have a similar problem to:
https://bitbucket.org/site/master/issue/3033/pushing-to-bitbucket-authorization-failed

I am setting up a new machine, cloning went fine, I've copied old ssh keys, but when doing hg push I get:

#!sh
hg push
pushing to ssh://hg@bitbucket/rkj/dotfiles
...
http authorization required
realm: Bitbucket.org HTTP
user: rkj
password: 
abort: authorization failed

I have no idea why it tries http instead of ssh for one, I've tried with https too:

#!sh

$ hg push
pushing to https://rkj@bitbucket.org/rkj/dotfiles
...
http authorization required
realm: Bitbucket.org HTTP
user: rkj
password: 
abort: authorization failed

I am pretty sure I am entering the right password (I've tried copy pasting the same thing to web UI...).
It could be that it's trying to push to some other repository, as I have couple of them in .hgsub, but there's no indication which one it would be. I did diff with -S and there are not changes in any subrepos. On my other machine where I have https clone the user is auto filled, here it's not...

I did the test from troubleshooting, and it seems ok:

#!sh

$ ssh -T hg@bitbucket.org
conq: logged in as rkj.

You can use git or hg to connect to Bitbucket. Shell access is disabled.

My hg version is 2.2.2