Merge branch 'en/rebase-x-wo-git-dir-env'

"git rebase -x" by mistake started exporting the GIT_DIR and GIT_WORK_TREE environment variables when the command was rewritten in C, which has been corrected. * en/rebase-x-wo-git-dir-env: sequencer: do not export GIT_DIR and GIT_WORK_TREE for 'exec'