D3187: phase: add dry-run functionality

[pulkit (Pulkit Goyal)]

pulkit added inline comments.

INLINE COMMENTS

> commands.py:3898
>                      if newdata[cl.rev(n)] < targetphase]
> +        if opts['dry_run']:
> +            rejected = []

Since all the logic is copy-pasted from phases.advanceboundary and phases.retractboundary, why not we just pass the `--dry-run` option there and get the count from those functions only.

> test-phases.t:990
> +  $ hg phase --draft 0 5 --force -n
> +  phase changed for 4 changesets
> +

This is not very much helpful. In such cases, how about showing the range of changesets, something like:

  f7b1eb17ad24::925d80f479bb public -> draft
  b385d13d5ed4::fdc0253c25cf secret -> draft

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D3187

To: khanchi97, pulkit, #hg-reviewers
Cc: av6, mercurial-devel