Windows: Fix opening file browser from webapp when repo is in a directory with spaces.

Assistant/WebApp/DashBoard.hs

@@ -118,20 +118,22 @@ openFileBrowser = do
 	path <- liftAnnex $ fromRepo Git.repoPath
 #ifdef darwin_HOST_OS
 	let cmd = "open"
-	let params = [Param path]
+	let p = proc cmd [path]
 #else
 #ifdef mingw32_HOST_OS
+	{- Changing to the directory and then opening . works around
+	 - spaces in directory name, etc. -}
 	let cmd = "cmd"
-	let params = [Param $ "/c start " ++ path]
+	let p = (proc cmd ["/c start ."]) { cwd = Just path }
 #else
 	let cmd = "xdg-open"
-	let params = [Param path]
+	let p = proc cmd [path]
 #endif
 #endif
 	ifM (liftIO $ inPath cmd)
 		( do
 			let run = void $ liftIO $ forkIO $ void $
-				boolSystem cmd params
+				createProcess p
 			run
 #ifdef mingw32_HOST_OS
 			{- On windows, if the file browser is not