The Go test suite adds remotes in the form of temporary bare Git
repositories, which lack a ".git" directory. These are then configured
with their local paths as the value of the "remote.origin.url" key,
which the EndpointFinder returns, but with "/.git" appended by the
EndpointFromLocalPath() function.
When the standalone transfer adapter attempts to chdir(2) to one of
these file paths in order to run the "git rev-parse --git-dir" command
when setting up a new handler, it obviously fails.
We can address this by simply removing any trailing "/.git" path
segment in the gitDirAtPath() function in the standalone adapter.
The "git rev-parse --git-dir" command will succeed in either case,
whether in a bare repository or a regular one.
This should permit any users who have Git LFS configurations with
custom adapters that depend on the EndpointFinder's current logic
to continue to work, while allowing our Go test suite to succeed
with its bare remote repositories.
One commonly requested feature for Git LFS is support for local files.
Currently, we tell users that they must use a standalone transfer
agent, which is true, but nobody has provided one yet. Since writing a
simple transfer agent is not very difficult, let's provide one
ourselves.
Introduce a basic standalone transfer agent, git lfs standalone-file,
that handles uploads and downloads. Add a default configuration required
for it to work, while still allowing users to override this
configuration if they have a preferred implementation that is more
featureful. We provide this as a transfer agent instead of built-in
because it avoids the complexity of adding a different code path to the
main codebase, but also serves as a demonstration of how to write a
standalone transfer agent for others who might want to do so, much
like Git demonstrates remote helpers using its HTTP helper.
