title: Ctrl+6 does not edit alternate buffer in Vim running in Terminal on macOS
body: <p>On my macOS High Sierra 10.13.6, I launch <code>vim</code> in Terminal and enter the following commands in Vim.</p>
  
  <pre><code>:e foo.txt
  :e bar.txt
  </code></pre>
  
  <p>Now if I press <kbd>Ctrl</kbd>+<kbd>6</kbd>, it does not go back to the alternate file <code>foo.txt</code>.</p>
  
  <p><kbd>Ctrl</kbd>+<kbd>Shift</kbd>+<kbd>6</kbd> works fine and does go back to the alternate file <code>foo.txt</code>.</p>
  
  <p>Every other Vim, MacVim, or GVim I have used goes back to the alternate file on pressing <kbd>Ctrl</kbd>+<kbd>6</kbd>. Why does it not work with <code>vim</code> of macOS?</p>
  
  <p>Here is my vim version details:</p>
  
  <pre><code>$ which vim
  /usr/bin/vim
  $ vim --version
  VIM - Vi IMproved 8.0 (2016 Sep 12, compiled Nov 29 2017 18:37:46)
  Included patches: 1-503, 505-680, 682-1283
  Compiled by root@apple.com
  Normal version without GUI.  Features included (+) or not (-):
  +acl             +file_in_path    -mouse_sgr       +tag_old_static
  -arabic          +find_in_path    -mouse_sysmouse  -tag_any_white
  +autocmd         +float           -mouse_urxvt     -tcl
  -balloon_eval    +folding         +mouse_xterm     -termguicolors
  -browse          -footer          +multi_byte      -terminal
  +builtin_terms   +fork()          +multi_lang      +terminfo
  +byte_offset     -gettext         -mzscheme        +termresponse
  +channel         -hangul_input    +netbeans_intg   +textobjects
  +cindent         +iconv           +num64           +timers
  -clientserver    +insert_expand   +packages        +title
  -clipboard       +job             +path_extra      -toolbar
  +cmdline_compl   +jumplist        -perl            +user_commands
  +cmdline_hist    -keymap          +persistent_undo +vertsplit
  +cmdline_info    +lambda          +postscript      +virtualedit
  +comments        -langmap         +printer         +visual
  -conceal         +libcall         -profile         +visualextra
  +cryptv          +linebreak       +python/dyn      +viminfo
  +cscope          +lispindent      -python3         +vreplace
  +cursorbind      +listcmds        +quickfix        +wildignore
  +cursorshape     +localmap        +reltime         +wildmenu
  +dialog_con      -lua             -rightleft       +windows
  +diff            +menu            +ruby/dyn        +writebackup
  +digraphs        +mksession       +scrollbind      -X11
  -dnd             +modify_fname    +signs           -xfontset
  -ebcdic          +mouse           +smartindent     -xim
  -emacs_tags      -mouseshape      +startuptime     -xpm
  +eval            -mouse_dec       +statusline      -xsmp
  +ex_extra        -mouse_gpm       -sun_workshop    -xterm_clipboard
  +extra_search    -mouse_jsbterm   +syntax          -xterm_save
  -farsi           -mouse_netterm   +tag_binary      
     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/share/vim"
  Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H   -DMACOS_X_UNIX  -g -O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1      
  Linking: gcc   -L/usr/local/lib -o vim        -lm -lncurses  -liconv -framework Cocoa           
  </code></pre>