outgoing: rework the handling of the `missingroots` case to be faster The previous implementation was slow, to the point it was taking a significant amount of `hg bundle --type none-streamv2` call. We rework the code to compute the same value much faster, making the operation disappear from the `hg bundle --type none-streamv2` profile. Someone would remark that producing a streamclone does not requires an `outgoing` object. However that is a matter for another day. There is other user of `missingroots` (non stream `hg bundle` call for example), and they will also benefit from this rework. We implement an old TODO in the process, directly computing the missing and common attribute as we have most element at hand already. ### benchmark.name = hg.command.bundle # bin-env-vars.hg.flavor = default # bin-env-vars.hg.py-re2-module = default # benchmark.variants.revs = all # benchmark.variants.type = none-streamv2 ## data-env-vars.name = heptapod-public-2024-03-25-zstd-sparse-revlog before: 7.750458 after: 6.665565 (-14.00%, -1.08) ## data-env-vars.name = mercurial-public-2024-03-22-zstd-sparse-revlog before: 0.700229 after: 0.496050 (-29.16%, -0.20) ## data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog before: 346.508952 after: 316.749699 (-8.59%, -29.76) ## data-env-vars.name = pypy-2024-03-22-zstd-sparse-revlog before: 3.401700 after: 2.915810 (-14.28%, -0.49) ## data-env-vars.name = tryton-public-2024-03-22-zstd-sparse-revlog before: 1.870798 after: 1.461583 (-21.87%, -0.41) note: this whole `missingroots` of outgoing has a limited number of callers and could likely be replace by something simpler (like taking an explicit "missing_revs" set for example). However this is a wider change and we focus on a small impact, quick rework that does not change the API for now.

  $ rm -rf a
  $ hg init a
  $ cd a
  $ echo a > a
  $ hg ci -Am0
  adding a
  $ hg tag t1 # 1
  $ hg tag --remove t1 # 2

  $ hg co 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg tag -f -r0 t1
  $ hg tags
  tip                                3:a49829c4fc11
  t1                                 0:f7b1eb17ad24

Ensure that the username access fails gracefully if assumptions about the
environment made by python do not hold.

#if windows
  >>> import os
  >>> from mercurial import util
  >>> os.environ.pop('LOGNAME', None) and None
  >>> os.environ.pop('USER', None) and None
  >>> os.environ.pop('LNAME', None) and None
  >>> os.environ.pop('USERNAME', None) and None
  >>> print(util.username())
  None
#endif

  $ cd ..