fix(repo): make sure --git-dir is always provided --work-tree

[lewis6991]

gitdir and worktree must be provided together. From man git:

Specifying the location of the ".git" directory using this option (or GIT_DIR environment
variable) turns off the repository discovery that tries to find a directory with ".git"
subdirectory (which is how the repository and the top-level of the working tree are
discovered), and tells Git that you are at the top level of the working tree. If you are
not at the top-level directory of the working tree, you should tell Git where the
top-level of the working tree is, with the --work-tree= option (or GIT_WORK_TREE
environment variable)

If not then toplevel can be incorrectly calculated.