Revert "Use --work-tree to fix :cd side effects in :Gcommit"
Revert "Use --work-tree to fix :cd side effects in :Gcommit"

This reverts commit 903ad4d70470fed5d73e1b0d61c1bbf42d19104c, which
broke :Gcommit when invoked from a subdirectory of the repository.

iff/dotfiles-old,iff/dotfiles-old