How to make git download a new folder after editing sparse-checkout?

Question

I have a git repo where I only want to download certain subfolders. My config looks like this:

#.git/config

[core]
    repositoryformatversion = 0
    filemode = true
    bare = false
    logallrefupdates = true
    sparsecheckout = true
[remote "dreamhost"]
  url = <repo url>
  fetch = +refs/heads/*:refs/remotes/dreamhost/*
[push]
  default = tracking  

In .git/info/sparse-checkout i had this:

themes/theme1
themes/theme8

which are the folders within the themes subfolder that I want to get. (I don't need the others, which are many).

If i do a git/pull I can see git fetching lots of stuff, including the themes subfolders which I don't want, which is fine. I know that sparse-checkout still pulls down the objects.

I now want to have a copy of themes/theme15, to make some changes. So, I edited .git/info/sparse-checkout thus:

themes/theme1
themes/theme8
themes/theme15

and then did a git pull dreamhost master, thinking that git would add the theme15 folder under themes. But, nothing happens - it just says

From <repo url>
 * branch            master     -> FETCH_HEAD
Already up-to-date.

and the folder's not there. Can anyone tell me what I'm doing wrong? Is there an extra step after editing .git/info/sparse-checkout?

thanks, Max

EDIT: this is in git version 2.8.1 btw

Answer 1

The step I needed to perform to make my folder appear after adding it to my sparse-checkout file was:

git read-tree -mu HEAD

Answer 2

Just figured this out, I'll answer it in case anyone else has the same problem.

After making the change I needed to do

git checkout themes/theme15

then the folder appears. Perhaps obvious in hindsight....(perhaps not).