Can't properly install plugin with branch specified

[Roy-Orbison]

Output from vim-plug:

  5 Updated. Elapsed time: 2.218548 sec.
  4 [===================x]
  3 
  2 - Finishing ... Done!
  1 x vim-taggatron:
6       fatal: invalid reference: issue/10

The plugin & branch, which Git and GitHub seem to accept without issue. The plugin does actually install but the output of git branch in ~/.vim/plugged/vim-taggatron is just this:

* master

I have to checkout the branch manually with git checkout issue/10:

Branch issue/10 set up to track remote branch issue/10 from origin.
Switched to a new branch 'issue/10'

I don't know if me doing that will mess up future updates.

---

VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Mar 27 2020 16:45:06)
Included patches: 1-460
Compiled by Roy
Huge version without GUI.  Features included (+) or not (-):
+acl               +channel           +cscope            +ex_extra          -hangul_input      +lispindent        -mouse_gpm         +netbeans_intg     +python/dyn        +spell             +terminal          +vertsplit         +X11
+arabic            +cindent           +cursorbind        +extra_search      +iconv             +listcmds          -mouse_jsbterm     +num64             +python3/dyn       +startuptime       +terminfo          +virtualedit       +xfontset
+autocmd           +clientserver      +cursorshape       -farsi             +insert_expand     +localmap          +mouse_netterm     +packages          +quickfix          +statusline        +termresponse      +visual            -xim
+autochdir         +clipboard         +dialog_con        +file_in_path      +job               -lua               +mouse_sgr         +path_extra        +reltime           -sun_workshop      +textobjects       +visualextra       +xpm
-autoservername    +cmdline_compl     +diff              +find_in_path      +jumplist          +menu              -mouse_sysmouse    +perl              +rightleft         +syntax            +textprop          +viminfo           +xsmp_interact
-balloon_eval      +cmdline_hist      +digraphs          +float             +keymap            +mksession         +mouse_urxvt       +persistent_undo   -ruby              +tag_binary        +timers            +vreplace          +xterm_clipboard
+balloon_eval_term +cmdline_info      -dnd               +folding           +lambda            +modify_fname      +mouse_xterm       +popupwin          +scrollbind        -tag_old_static    +title             +wildignore        -xterm_save
-browse            +comments          -ebcdic            -footer            +langmap           +mouse             +multi_byte        +postscript        +signs             -tag_any_white     -toolbar           +wildmenu
++builtin_terms    +conceal           +emacs_tags        +fork()            +libcall           -mouseshape        +multi_lang        +printer           +smartindent       -tcl               +user_commands     +windows
+byte_offset       +cryptv            +eval              +gettext           +linebreak         +mouse_dec         -mzscheme          +profile           -sound             +termguicolors     +vartabs           +writebackup
   system vimrc file: "$VIM/vimrc"
     user vimrc file: "$HOME/.vimrc"
 2nd user vimrc file: "~/.vim/vimrc"
      user exrc file: "$HOME/.exrc"
       defaults file: "$VIMRUNTIME/defaults.vim"
  fall-back for $VIM: "/usr/local/share/vim"
Compilation: gcc -std=gnu99 -c -I. -Iproto -DHAVE_CONFIG_H     -O -I/usr/lib64/perl5/CORE/ -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1     -I/usr/include64
Linking: gcc -std=gnu99  -L/usr/lib64   -Wl,--enable-new-dtags -Wl,-rpath,/usr/lib64/perl5/CORE   -L/usr/local/lib -Wl,--as-needed -o vim    -lSM -lICE -lXpm -lXt -lX11 -lSM -lICE  -lm -ltinfo -lnsl    -ldl   -Wl,--enable-new-dtags -Wl,-rpath,/usr/lib64/perl5/CORE  -fstack-protector  -L/usr/lib64/perl5/CORE -lperl -lresolv -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc

• Type:
  • Bug
  • Enhancement
  • Feature Request
  • Question
• OS:
  • All/Other
  • Linux
  • OS X
  • Windows
• Vim:
  • Terminal Vim
  • GVim
  • Neovim

[Roy-Orbison]

I don't know for sure that the / is the cause, but removing the branch specifier allows the installation without error.

BTW, my Git is version 1.8.3.1.

[Roy-Orbison]

The answer is in the bug report, I just didn't realise. It's not the branch name. I tried with this entry:

Plug 'joonty/vim-taggatron', {'branch': 'python3'}

It failed again. I ran the same branch checkout your code does, manually:

git checkout -q python3 -- 2>&1

It failed with the same message and, as before, running a simple checkout worked fine:

git checkout python3

The -- without any paths specified after it breaks the checkout.

[Roy-Orbison]

It wasn't that simple, either. This works:

git checkout -q --track origin/python3 -- 2>&1

When installing a plugin, I think it should be explicit about tracking the remote branch.

I know the manual has this

git checkout [<branch>]
...
If <branch> is not found but there does exist a tracking branch in exactly one remote (call it <remote>) with a matching name and --no-guess is not specified, treat as equivalent to

   $ git checkout -b <branch> --track <remote>/<branch>

And it does do that but only interactively or without a paths separator, or something, but it's defeinitely failing in my older git unless it specifies remote tracking.

[Roy-Orbison]

Can we just add a check to see whether the local branch exists, and if not, add the --track flag to this command?

vim-plug/plug.vim

Line 1297 in 8b45742

let out = s:system('git checkout -q '.plug#shellescape(branch).' -- 2>&1'

[Roy-Orbison]

This patch solves the initial install for me, I'll let you know how updates go. It puts the plugin repo into a detached HEAD state like the tag option.

--- a/.vim/autoload/plug.vim     2021-02-19 11:00:37.100186300 +1030
+++ b/.vim/autoload/plug.vim     2021-02-19 11:00:37.081185977 +1030
@@ -1295,9 +1295,8 @@
         let out = s:system('git checkout -q '.plug#shellescape(tag).' -- 2>&1', spec.dir)
       else
         let branch = s:git_origin_branch(spec)
-        call s:log4(name, 'Merging origin/'.s:esc(branch))
-        let out = s:system('git checkout -q '.plug#shellescape(branch).' -- 2>&1'
-              \. (has_key(s:update.new, name) ? '' : ('&& git merge --ff-only '.plug#shellescape('origin/'.branch).' 2>&1')), spec.dir)
+        call s:log4(name, 'Checking out origin/'.s:esc(branch))
+        let out = s:system('git checkout -q origin/'.plug#shellescape(branch).' -- 2>&1', spec.dir)
       endif
       if !v:shell_error && filereadable(spec.dir.'/.gitmodules') &&
             \ (s:update.force || has_key(s:update.new, name) || s:is_updated(spec.dir))

[taqenoqo]

This problem will always occur if the following is specified in the gitconfig file, regardless of the version of Git you are using.

[checkout]
	guess = false

This type of checkout method used in vim-plug is apparently called "guess". If you use this feature, you must explicitly specify the --guess option; otherwise, depending on your Git settings, the checkout will definitely fail.