Avoid breaking tab-local directory settings

Neovim has support for tab-local settings, additionally to global and
window-local.

When a tab is set with `tcd`, if the directory is changed with `cd`, the
tab-local setting is discarded.

This patch fixes the current bug by setting checking the granularity of current
setting prior to changing directory.

autoload/magit/git.vim

@@ -50,15 +50,15 @@ endfunction
 function! magit#git#is_work_tree(path)
 	let dir = getcwd()
 	try
-		call magit#utils#lcd(a:path)
+		call magit#utils#chdir(a:path)
 		let top_dir=magit#utils#strip(
 					\ system(g:magit_git_cmd . " rev-parse --show-toplevel")) . "/"
 		if ( v:shell_error != 0 )
 			return ''
 		endif
 		return top_dir
 	finally
-		call magit#utils#lcd(dir)
+		call magit#utils#chdir(dir)
 	endtry
 endfunction
 
@@ -68,7 +68,7 @@ endfunction
 function! magit#git#set_top_dir(path)
 	let dir = getcwd()
 	try
-		call magit#utils#lcd(a:path)
+		call magit#utils#chdir(a:path)
 		let top_dir=magit#utils#strip(
 					\ system(g:magit_git_cmd . " rev-parse --show-toplevel")) . "/"
 		if ( v:shell_error != 0 )
@@ -81,7 +81,7 @@ function! magit#git#set_top_dir(path)
 		let b:magit_top_dir=top_dir
 		let b:magit_git_dir=git_dir
 	finally
-		call magit#utils#lcd(dir)
+		call magit#utils#chdir(dir)
 	endtry
 endfunction
 

autoload/magit/state.vim

@@ -274,7 +274,7 @@ function! magit#state#update() dict
 
 	let dir = getcwd()
 	try
-		call magit#utils#lcd(magit#git#top_dir())
+		call magit#utils#chdir(magit#git#top_dir())
 		call magit#utils#refresh_submodule_list()
 		for [mode, diff_dict_mode] in items(self.dict)
 			let status_list = magit#git#get_status()
@@ -289,7 +289,7 @@ function! magit#state#update() dict
 			endfor
 		endfor
 	finally
-		call magit#utils#lcd(dir)
+		call magit#utils#chdir(dir)
 	endtry
 
 	" remove files that have changed their mode or been committed/deleted/discarded...

autoload/magit/utils.vim

@@ -20,12 +20,17 @@ function! magit#utils#is_submodule(dirname)
 	return ( index(s:submodule_list, a:dirname) != -1 )
 endfunction
 
-" s:magit_cd_cmd: plugin variable to choose lcd/cd command, 'lcd' if exists,
-" 'cd' otherwise
-let s:magit_cd_cmd = exists('*haslocaldir') && haslocaldir() ? 'lcd ' : 'cd '
-" magit#utils#lcd: helper function to lcd. use cd if lcd doesn't exists
-function! magit#utils#lcd(dir)
-	execute s:magit_cd_cmd . fnameescape(a:dir)
+" magit#utils#chdir will change the directory respecting
+" local/tab-local/global directory settings.
+function! magit#utils#chdir(dir)
+  " This is a dirty hack to fix tcd breakages on neovim.
+  " Future work should be based on nvim API.
+  if exists(':tcd')
+    let chdir = haslocaldir() ? 'lcd' : haslocaldir(-1, 0) ? 'tcd' : 'cd'
+  else
+    let chdir = exists('*haslocaldir') && haslocaldir() ? 'lcd' : 'cd'
+  endif
+  execute chdir fnameescape(a:dir)
 endfunction
 
 " magit#utils#clear_undo: this function clear local undo history.
@@ -55,7 +60,7 @@ endfunction
 function! magit#utils#system(...)
 	let dir = getcwd()
 	try
-		call magit#utils#lcd(magit#git#top_dir())
+		call magit#utils#chdir(magit#git#top_dir())
 		" List as system() input is since v7.4.247, it is safe to check
 		" systemlist, which is sine v7.4.248
 		if exists('*systemlist')
@@ -75,7 +80,7 @@ function! magit#utils#system(...)
 			endif
 		endif
 	finally
-		call magit#utils#lcd(dir)
+		call magit#utils#chdir(dir)
 	endtry
 endfunction
 
@@ -88,15 +93,15 @@ endfunction
 function! magit#utils#systemlist(...)
 	let dir = getcwd()
 	try
-		call magit#utils#lcd(magit#git#top_dir())
+		call magit#utils#chdir(magit#git#top_dir())
 		" systemlist since v7.4.248
 		if exists('*systemlist')
 			return call('systemlist', a:000)
 		else
 			return split(call('magit#utils#system', a:000), '\n')
 		endif
 	finally
-		call magit#utils#lcd(dir)
+		call magit#utils#chdir(dir)
 	endtry
 endfunction