Disable auto-completion of remote branches in Git Bash?

With Git 2.13 (Q2 2017), you can disable (some of) the branch completion.

git checkout --no-guess ...
# or:
export GIT_COMPLETION_CHECKOUT_NO_GUESS=1

See commit 60e71bb (21 Apr 2017) by Jeff King (peff).
^{(Merged by Junio C Hamano -- gitster -- in commit b439747, 01 May 2017)}

As documented in contrib/completion/git-completion.bash now:

You can set the following environment variables to influence the behavior of the completion routines:

GIT_COMPLETION_CHECKOUT_NO_GUESS

When set to "1", do not include "DWIM" suggestions in git-checkout completion (e.g., completing "foo" when "origin/foo" exists).

Note: DWIM is short for Do What I Mean, where a system attempts to anticipate what users intend to do, correcting trivial errors automatically rather than blindly executing users' explicit but potentially incorrect inputs.

completion: optionally disable checkout DWIM

When we complete branch names for "git checkout", we also complete remote branch names that could trigger the DWIM behavior. Depending on your workflow and project, this can be either convenient or annoying.

For instance, my clone of gitster.git contains 74 local "jk/*" branches, but origin contains another 147.
When I want to checkout a local branch but can't quite remember the name, tab completion shows me 251 entries. And worse, for a topic that has been picked up for pu, the upstream branch name is likely to be similar to mine, leading to a high probability that I pick the wrong one and accidentally create a new branch.

---

Note: "picked up for pu": see a What's cooking in git.git: it starts with:

Commits prefixed with '-' are only in 'pu' (proposed updates) while commits prefixed with '+' are in 'next'.

This is part of the Git Workflow Graduation process.

pu (proposed updates) is an integration branch for things that are not quite ready for inclusion yet

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This patch adds a way for the user to tell the completion code not to include DWIM suggestions for checkout.
This can already be done by typing:

git checkout --no-guess jk/<TAB>

but that's rather cumbersome.

The downside, of course, is that you no longer get completion support when you do want to invoke the DWIM behavior.
But depending on your workflow, that may not be a big loss (for instance, in git.git I am much more likely to want to detach, so I'd type "git checkout origin/jk/<TAB>" anyway).

I'm assuming that you are using the git-completion.bash script, and that you only care about git checkout.

To accomplish this, I just changed one line in the definition of the _git_checkout () function in git-completion.bash:

<       __gitcomp_nl "$(__git_refs '' $track)"
---
>       __gitcomp_nl "$(__git_heads '' $track)"

My understanding is that this only affects the tab-completion action (because of its location within the * case of the switch-case statement).

If you installed git-completion via homebrew, it's located here: /usr/local/etc/bash_completion.d/git-completion.bash

Following erik.weathers' answer above, I made the following change so autocompletion can work for both local and remote based on the current prefix. By default, it'll only search local, but if I specify origin/… it'll know I want to search remote branches too.

In the _git_checkout () method, change

    __gitcomp_nl "$(__git_refs '' $track)"

to:

    # only search local branches instead of remote branches if origin isn't specified
    if [[ $cur == "origin/"* ]]; then
        __gitcomp_nl "$(__git_refs '' $track)"
    else
        __gitcomp_nl "$(__git_heads '' $track)"
    fi

Of course, you can change origin to something else or you can have it search through through a list of remote prefixes if you have more than 1.