git-worktree functionality for managing multiple working trees

[nelsonni]

Description:

Cards linked to files on git branches that do not match the current repository branch have previously required creating temporary shadow clones of the repository in order to switch branches and copy the necessary files. This process is costly and also leaves no recourse for any subsequent changes to be saved and tracked via version control.

git-worktree provides the ability to manage multiple working trees:

A git repository can support multiple working trees, allowing you to check out more than one branch at a time. With git worktree add a new working tree is associated with the repository. This new working tree is called a "linked working tree" as opposed to the "main working tree" prepared by git-init[1] or git-clone[1]. A repository has one main working tree (if it’s not a bare repository) and zero or more linked working trees. When you are done with a linked working tree, remove it with git worktree remove.

In its simplest form, git worktree add automatically creates a new branch whose name is the final component of , which is convenient if you plan to work on a new topic. For instance, git worktree add ../hotfix creates new branch hotfix and checks it out at path ../hotfix. To instead work on an existing branch in a new working tree, use git worktree add . On the other hand, if you just plan to make some experimental changes or do testing without disturbing existing development, it is often convenient to create a throwaway working tree not associated with any branch. For instance, git worktree add -d creates a new working tree with a detached HEAD at the same commit as the current branch.

Implementing git-worktree within isomoprhic-git would be ideal, but until then we can wrap the functionality of git-worktree around the necessary functions exposed by isomorphic-git. The following functions must be implemented:

• git-worktree.add
• git-worktree.list
• git-worktree.lock
• git-worktree.move
• git-worktree.prune
• git-worktree.remove
• git-worktree.repair
• git-worktree.unlock

This PR resolves #69, and signifies the following version changes:

• MAJOR version increase
• MINOR version increase
• PATCH version increase

Changes:

This PR makes the following changes:

• git-worktree.add function creates a new linked worktree directory outside of the main worktree directory and checks out the target commit-ish branch/commit.
• git-worktree.list returns a formatted collection of Worktree objects containing a path to the linked worktree root directory, a branch name or symbolic ref pointed to by each worktree, a SHA-1 hash for the revision/commit that represents the current state of the worktree index, and indicators for bare repository and detached state statuses.
• git-worktree.prune for removing entries from the $GIT_DIR/worktrees directory for any linked worktrees that have subsequently seen their worktree root directory deleted.
• git-worktree.remove for cleanly removing a linked worktree (including entries in $GIT_DIR/worktrees); requires the use of the force parameter for unclean worktrees (untracked files or modifications in tracked files) or ones with submodules.

Checklist:

Before submitting this PR, I have verified that my code:

• Resides on a fix/ or feat/ branch that was initially branched off from development.
• Passes code linting (yarn lint) and unit testing (yarn test).
• Successfully builds a distribution package (yarn package).

Additionally, I have verified that:

• My name is listed in the Contributors section, or this PR includes a request to add my name.
• I have read and am aware of the CONTRIBUTING guide for this project.

[nelsonni]

@jettseale This PR is currently a draft, but please try out the tests to see if anything breaks on your Windows system.

[jettseale]

When I ran yarn test, one of the tests errored and five of them failed. Below are screenshots of the failing and erroring tests:

[jettseale]

When I ran yarn test, I got two failing tests in the git-worktree.add suite:

Looks like a simple Windows pathing issue.

[jettseale]

Looks like the fix caused new errors for those same two tests: