title: vim help produces "unable to open swap file" error
body: <p>In vim, frequently when I perform a ':help ' command, I get an error. Here's an error I see when I perform ':help tags' for example:</p>
  
  <pre><code>"tagsrch.txt.gz" [readonly][noeol] 42L, 11288C
  Error detected while processing function gzip#read:
  line   51:
  E303: Unable to open swap file for "/usr/share/vim/vim74/doc/tagsrch.txt.gz", recovery impossible
  41 fewer lines
  Press ENTER or type command to continue
  </code></pre>
  
  <p>When I press enter, the help comes up as desired, but this is still a nuisance. What have I done wrong? My google-foo is apparently too weak for this because I don't see other people complaining about this.</p>
  
  <p>Is this because I have this set for my swap directory?</p>
  
  <pre><code>set directory=~/.vim/swap,.
  </code></pre>
  
  <p>Let me know if it would be helpful to paste my entire vimrc. I'm on rhel7 with vim 7.4, in case it's helpful.</p>
  
  <p>Here's my <code>~/.vimrc</code>:</p>
  
  <pre><code>" vim:softtabstop=4:shiftwidth=4:et
  " Tab preferences
  set shiftwidth=4
  set softtabstop=4
  set autoindent
  set expandtab
  
  execute pathogen#infect()
  
  " Where to store swap files.  By default, they will go into ~/.vim/swap, but
  " if that doesn't work, they will go in cwd.
  set directory=~/.vim/swap,.
  
  filetype plugin indent on   " enables filetype indent specific plugins
  
  " Instructions on how to tab complete filenames.
  " set wildmode=longest,list,full
  set wildmode=longest,list
  set wildmenu
  
  " In case there are vim modelines at the top of the file, as there
  " is with this one.
  set modeline
  
  " Always show the status line.
  set laststatus=2
  
  " Look for a tags file.
  set tags=./tags,tags;
  " Also search for .git/tags files.
  set tags^=./.git/tags,*/.git/tags;~
  
  " Make Ctrl-] show the list of options by default.
  nnoremap &lt;C-]&gt; g&lt;C-]&gt;
  nnoremap &lt;C-w&gt;&lt;C-]&gt; &lt;C-w&gt;g&lt;C-]&gt;
  
  " Colors
  " Have syntax highlighting in terminals which can display colours:
  if has('syntax') &amp;&amp; (&amp;t_Co &gt; 2)
    syntax on
  else
    syntax off
  endif
  set background=dark
  set hlsearch
  set incsearch
  
  " I so often type teh instead of the.
  abbreviate teh the
  
  " To help vim deal with pasting text
  :map &lt;F9&gt; :set invpaste &lt;CR&gt;
  set pt=&lt;F9&gt;
  
  " Toggle vim's spell checker with &lt;F5&gt;
  :map &lt;F5&gt; :setlocal spell! spelllang=en_us&lt;cr&gt;
  
  " Shortcuts for c code.
  map! ,bc /*  */^[hhi
  map! ,bz #if 0^M#endif /* 0 */^[O
  
  " Ignore whitespace when diffing files.
  map ,iw :set diffopt+=iwhite&lt;CR&gt;
  set path^=/home/bneradt/work/trafficserver/**
  </code></pre>