Shelly (https://github.com/davidh-raybeam/shelly) script for a git shell with a nice prompt and tab completion for remotes and branches.

gitsh

#!/usr/bin/env ruby

require 'shelly'
require 'shellwords'
include Shelly

$YELLOW = `tput setaf 3`
$BLUE   = `tput setaf 4`
$WHITE  = `tput setaf 7`
$RESET  = `tput sgr0`

def is_git?
  system('git log &>/dev/null')
end

def branch
  branches = `git branch 2>/dev/null`.each_line.to_a
  active_branch = branches.select { |b| b =~ %r/^\*/ }.first
  active_branch.strip.gsub(%r/^\* (.*)$/) { $1 }
end

def changes?
  `git status --porcelain 2>/dev/null`.strip.length > 0
end

def all_branches
  branches = []
  `git branch 2>/dev/null`.each_line do |line|
    branches << line.strip.gsub(%r/^\* /, '')
  end
  branches
end

def all_remotes
  `git remote 2>/dev/null`.each_line.to_a.collect(&:strip)
end

# Custom command: \grep
command 'grep',
    description: 'searches the repo for the given pattern',
    usage: '\grep PATTERN' do |shell, argstring|
  system "egrep #{argstring} -r . -n --exclude='*.git*' --color=tty"
  puts; puts
end

# Prompt:
#   [current_branch]±     (when there are no uncommitted changes)
#   [current_branch(!)]±  (when there are uncommitted changes)
#   ??                    (when cwd is not a git repo)
prompt do |cont|
  if cont
    "#{$WHITE}> #{$RESET}"
  else
    if is_git?
      if changes?
        changestr = "#{$YELLOW}(!)"
      else
        changestr = ""
      end
      "#{$WHITE}[#{$BLUE}#{branch}#{changestr}#{$WHITE}]\u00b1 #{$RESET}"
    else
      "#{$YELLOW}?? #{$RESET}"
    end
  end
end

# Tab-completion:
#   If the partial matches any branches or remotes, return those.
#   If not, fall back to filenames.
#   NOTE: if you want filenames, branches, and remotes to have the same
#         priority, change tab_complete's first argument to :filenames
tab_complete :filenames_after do |partial|
  candidates = all_branches + all_remotes
  matches = candidates.grep %r/^#{Regexp.escape partial}/
  if matches.length == 1
    [matches[0] + ' ']
  else
    matches
  end
end

shelly 'git'