Fix hardcoded shellslashes for helptags()

[sofaking]

Fix is obvious and don't need any comments.
But it took a lot of time, because I've never seen vim-script before :)

[tpope]

Happy to merge, but was this actually breaking helptags on Windows? Surprised this is the first I've heard of it.

[sofaking]

Surely, absence of helptags was the reason for my acquaintance with vim-script. Strange but seems like no one uses vim-rails under Win.

[tpope]

I just booted up my Windows VM and verified it does indeed generate tags on it. Were you getting an error, or just silent failure? You do not have 'shellslash' set, correct?

[sofaking]

Aha I don't.
Not quite silent. I got E149: Sorry, no help for rails after entered :help rails

[tpope]

'shellslash' is mainly used with setups like Cygwin. I don't have it set either (but it can be relevant so I thought I'd ask).

I was looking for an error on :call pathogen#helptags() or :Helptags, not the actual :help invocation.

I've gone ahead and merged in your changes, but I'd still like to isolate the cause, so that I can determine the priority of cutting a new release. If I can't find anything, I'm going to assume it's something really weird in your setup, and hold off on a release.

[sofaking]

Now I know why your plugins are so popular. Because of serious approach ;)
I don't have Cygwin. Just clean gvim setup. On Cygwin, I suppose, shellslashes is *nix-like, so there are no problems.
For me it's more than obvious that standard slashes can't be used on Win platform.

[tpope]

Obvious perhaps, but completely untrue. :echo isdirectory('C:/Windows') returns 1 (true). :e ~/_vimrc correctly edits the file. The only reason I bother with backslashes at all is so 'runtimepath' isn't an ugly mixture of the two. Something is broken on your machine. You can start investigating by running those two commands and seeing if they work for you.

[sofaking]

Maybe we should check does filewritable() work with slashes under Win. I can't do it myself, I dunno how ;) I tried :call filewritable($HOME) from gvim, but it returned nothing.

Aslo, maybe this will help: http://vim.1045645.n5.nabble.com/Windows-path-and-quot-quot-HOME-td1151589.html
The guy said:

This depends on context. When Vim knows that some
value is a file/folder name, it will usually interpret any of '/', ''
or '' as a path separator, to be passed to the OS as a single
backslash, except where a backslash is obviously meant as an escape
prefix.

[tpope]

:echo not :call