histedit: use rewriteutil.precheck() instead of reimplementing it We have had this nice utility since 490df753894d (rewriteutil: add a precheck function to check if revs can be rewritten, 2017-11-24). We got two callers soon thereafter, in 98f97eb20597 (rewriteutil: use precheck() in uncommit and amend commands, 2017-11-28). It's about time we use it in other places. rewriteutil.precheck() looks unfortunate for i18n (it seems to rely on an English verb for the action making sense in other languages), but hopefully not bad enough that we should avoid using it. Differential Revision: https://phab.mercurial-scm.org/D7684

rebase: inline single-use variables passed to _definedestmap() Differential Revision: https://phab.mercurial-scm.org/D7646

rebase: use cmdutil.check_at_most_one_arg() for action+revision Differential Revision: https://phab.mercurial-scm.org/D7645

rebase: use cmdutil.check_incompatible_arguments() for --auto-orphans Differential Revision: https://phab.mercurial-scm.org/D7644

rebase: use cmdutil.check_at_most_one_arg() for -b/-s/-r Differential Revision: https://phab.mercurial-scm.org/D7643

rebase: inline single-use `dryrun` and `confirm` variables Differential Revision: https://phab.mercurial-scm.org/D7642