Merge branch 'ds/for-each-repo-w-worktree'

"git for-each-repo" started from a secondary worktree did not work
as expected, which has been corrected.

* ds/for-each-repo-w-worktree:
  for-each-repo: simplify passing of parameters
  for-each-repo: work correctly in a worktree
  run-command: extract sanitize_repo_env helper
  for-each-repo: test outside of repo context

diff --cc run-command.c
Simple merge

diff --cc run-command.h
Simple merge