Possible fix for #642.

When using a custom Wiki2HTML on Windows the normalized paths caused the
closing quote to be escaped and not pass the correct arguments to the
system call. This fix removes the trailing slash for Windows while
leaving the default behavior the same.

autoload/vimwiki/html.vim

@@ -1418,24 +1418,38 @@ function! s:use_custom_wiki2html()
         \ (s:file_exists(custom_wiki2html) || s:binary_exists(custom_wiki2html))
 endfunction
 
-
 function! vimwiki#html#CustomWiki2HTML(path, wikifile, force)
   call vimwiki#path#mkdir(a:path)
+
+  " fix for trailing / causing " to be escaped on windows, see #642
+  if has('win16') || has('win95') || has('win32') || has('win64')
+    let l:path = substitute(a:path, '\\$', '', '')
+    let l:css = substitute(shellescape(s:default_CSS_full_name(a:path)), '\\$', '', '')
+    " template path ends in / even on windows hence the different substitute
+    let l:tmpl = shellescape(expand(substitute(vimwiki#vars#get_wikilocal('template_path'), '/$', '', '')))
+    let l:rpath = substitute(shellescape(s:root_path(vimwiki#vars#get_bufferlocal('subdir'))), '\\$', '', '')
+  else
+    let l:path = a:path
+    let l:css = shellescape(s:default_CSS_full_name(a:path))
+    let l:tmpl = shellescape(expand(vimwiki#vars#get_wikilocal('template_path')))
+    let l:rpath = shellescape(s:root_path(vimwiki#vars#get_bufferlocal('subdir')))
+  endif
+
   echomsg system(vimwiki#vars#get_wikilocal('custom_wiki2html'). ' '.
       \ a:force. ' '.
       \ vimwiki#vars#get_wikilocal('syntax'). ' '.
       \ strpart(vimwiki#vars#get_wikilocal('ext'), 1). ' '.
-      \ shellescape(a:path). ' '.
+      \ shellescape(l:path). ' '.
       \ shellescape(a:wikifile). ' '.
-      \ shellescape(s:default_CSS_full_name(a:path)). ' '.
+      \ l:css . ' '.
       \ (len(vimwiki#vars#get_wikilocal('template_path')) > 1 ?
-      \     shellescape(expand(vimwiki#vars#get_wikilocal('template_path'))) : '-'). ' '.
+      \     l:tmpl : '-'). ' '.
       \ (len(vimwiki#vars#get_wikilocal('template_default')) > 0 ?
       \     vimwiki#vars#get_wikilocal('template_default') : '-'). ' '.
       \ (len(vimwiki#vars#get_wikilocal('template_ext')) > 0 ?
       \     vimwiki#vars#get_wikilocal('template_ext') : '-'). ' '.
       \ (len(vimwiki#vars#get_bufferlocal('subdir')) > 0 ?
-      \     shellescape(s:root_path(vimwiki#vars#get_bufferlocal('subdir'))) : '-'). ' '.
+      \     l:rpath : '-'). ' '.
       \ (len(vimwiki#vars#get_wikilocal('custom_wiki2html_args')) > 0 ?
       \     vimwiki#vars#get_wikilocal('custom_wiki2html_args') : '-'))
 endfunction