tests/test-obsolete-bounds-checking.t

rhg: read [paths] for `--repository` value

hg parses `-R` and `--repository` CLI arguments "early" in order to know which
local repository to load config from. (Config can then affect whether or how to
fall back.)

The value of of those arguments can be not only a filesystem path, but also an
alias configured in the `[paths]` section. This part was missing in rhg and
this patch implements that.

The current patch still lacks functionality to read config of current repository
if we are not at root of repo. That will be fixed in upcoming patches.

A new crate `home` is added to get path of home directory.

Differential Revision: https://phab.mercurial-scm.org/D10296

Create a repo, set the username to something more than 255 bytes, then run hg amend on it.

  $ unset HGUSER
  $ cat >> $HGRCPATH << EOF
  > [ui]
  > username = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa <[e-mail]>
  > [extensions]
  > amend =
  > [experimental]
  > evolution.createmarkers=True
  > evolution.exchange=True
  > EOF
  $ hg init tmpa
  $ cd tmpa
  $ echo a > a
  $ hg add
  adding a
  $ hg commit -m "Initial commit"
  $ echo a >> a
  $ hg amend 2>&1 | egrep -v '^(\*\*|  )'
  transaction abort!
  rollback completed
  Traceback (most recent call last):
  *ProgrammingError: obsstore metadata value cannot be longer than 255 bytes (value "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa <[e-mail]>" for key "user" is 285 bytes) (glob)