[PATCH v1 00/11] Improve git gui operation without a worktree

git gui has a number of inter-related problems that result in problems
during startup from anything but a checked out worktree pointing at a
valid git repository. Some of the symptoms are:
- blame / browser subcommands, and launching gitk, are intended to be
  useful without a worktree, but fail to work.
- unlike git, git-gui is supposed to use the parent directory as a
  worktree if started from the .git subdirectory in the very common
  single worktree + embedded git repository format. This does not
  work.
- git-gui includes a repository picker allowing a user select a worktree
  from a list and/or start a new repo+worktree: this dialog appears at
  unexpected times, masking useful error feedback on configuration
  problems.

This patch series addresses the above issues, substantially rewriting the blame / browser command line process, the initial repository and worktree discovery processes, and using git rev-parse when possible to handle repository / worktree discovery including any specification of GIT_DIR or GIT_WORK_TREE to reduce the future likelihood of conflict with command line git. This also allows explicit user control to avoid the repository picker masking a configuration error.

Note: I question why git-gui ever exports GIT_WORK_TREE. If it is not
empty, that is the current directory when startup is complete and any
git command will use the current directory as the worktree. If empty,
there is no worktree and the current directory should be (and after this
series, is) at the toplevel of the gitdir: again, there is nothing to
communicate to another process. If a process being launched needs a
different worktree, that should be the startup directory given to the
process without changing git-gui's current directory.

Mark Levedahl (11):
  git-gui: allow specifying path '.' to the browser
  git-gui: refactor browser / blame argument parsing
  git-gui: guard set/unset of GIT_DIR and GIT_WORK_TREE
  git-gui: put choose_repository::pick in a proc
  git-gui: use --absolute-git-dir
  git gui: GIT_DIR / GIT_WORK_TREE make any discovery error fatal
  git-gui: use rev-parse exclusively to find a repository
  git-gui: simplify [is_bare] to report if a worktree is known
  git-gui: support using repository parent dir as a worktree
  git-gui: improve worktree discovery
  git-gui: add gui and pick as explicit subcommands

 git-gui.sh | 276 ++++++++++++++++++++++++++---------------------------
 1 file changed, 135 insertions(+), 141 deletions(-)