Git push completion not working for branch (second argument) - bash

Question

So I have downloaded the git-completion.bash from here as you can see from the following output:
$ ls ~ | grep git-completion
-rw-r--r-- 1 waldyr staff 64720 Jul 21 23:43 .git-completion.bash
I'm running macOS High Sierra version 10.13.6 and I downloaded bash-completion using homebrew as you can see from the following output:
$ brew info bash-completion
bash-completion: stable 1.3 (bottled)
Programmable completion for Bash 3.2
https://salsa.debian.org/debian/bash-completion
Conflicts with:
bash-completion#2 (because Differing version of same formula)
/usr/local/Cellar/bash-completion/1.3_3 (189 files, 608.2KB) *
Poured from bottle on 2018-07-18 at 11:25:01
From: https://github.com/Homebrew/homebrew-core/blob/master/Formula/bash-completion.rb
==> Caveats
Add the following line to your ~/.bash_profile:
[ -f /usr/local/etc/bash_completion ] && . /usr/local/etc/bash_completion
Bash completion has been installed to:
/usr/local/etc/bash_completion.d
My .bash_profile sources a file called .bashrc which sources both bash-completion and git completion with telling the :
$ cat ~/.bash_profile
. ~/.bashrc
$ cat ~/.bashrc
[ -f /usr/local/etc/bash_completion ] && . /usr/local/etc/bash_completion
if [ -f ~/.git-completion.bash ]; then
source ~/.git-completion.bash
__git_complete gp _git_push
fi
alias gp='git push'
Whenever I type gp in the terminal and press tab asking for completion the script works perfectly:
$ gp <tab>
origin production
And after my selection of a repository the completion doesn't work for the refspec:
When there's nothing after it keeps showing the repositories:
$ gp origin <tab>
origin production
If there's at least one letter it (for example m from master), it looks for the files in the current directory
$ gp origin m<tab>
Makefile Minafile
I know I can alias git in the bashrc to g and alias git-push in gitconfig to p making the command g p which the completion works perfectly but I find annoying having to type the space.
What am I missing to make the completion work for the second argument (refspec)? Is that a git bug?
Here is the link for my dotfiles so you can check the whole files.