Use scope-local functions

[hkupty]

This avoids overriding local cwd settings, as vim allows lcd
for window-local working directory and neovim supports additionally tcd
for tab-local working directory.

[justinmk]

In every case that I see, the CWD directory is restored in a finally block. So why does it matter if lcd or cd or tcd is used?

[hkupty]

The bug occurs when you have two tabs with different tcds set.

When the plugin runs on the first tab, apparently nothing happens, but the setting has changed the scope back to global.

When running on the second tab, the plugin changes the setting of that tab back to global, and both tabs now are located on the cwd of the latter.

Took me a while to figure this out.

[hkupty]

Also, it's important to say that I tested this on jreybert/vimagit#95, mhinz/vim-signify#192 and this one and all these three plugins were causing the same issue. While neomake/neomake#688 has the same pattern, I couldn't prove it was offending.

Basically any plugin that does not support tcd will break its usage after some time.

[hkupty]

ping @ludovicchabant. Can we merge?

[ludovicchabant]

Ah sorry, totally didn't see this pull request. Thanks, I had not considered local CWDs.

However it looks like the version of getcwd that takes parameters is fairly new? It doesn't work on one of my machines that still has Vim 7.4. Is there a backwards compatible way to get a windows' local dir?

[hkupty]

No problem.

I've been on a hurry lately, sorry about that.

About what you said I'm not sure since when it's available, but it looks like it has something to do with lcd, so we could add a check for lcd on that as well..

[ludovicchabant]

Merged, thanks a lot!