BUG: rolling with axis=1
- [x] fixes #13753 
- [ ] tests added / passed
- [x] passes `git diff upstream/master | flake8 --diff`
- [ ] whatsnew entry

tests!
 On it! Clearly new to TDD but will take a stab.
 [contributing guide](http://pandas.pydata.org/pandas-docs/stable/contributing.html)
 ## [Current coverage](https://codecov.io/gh/pydata/pandas/pull/13757?src=pr) is 84.56% (diff: 100%)

> Merging [#13757](https://codecov.io/gh/pydata/pandas/pull/13757?src=pr) into [master](https://codecov.io/gh/pydata/pandas/branch/master?src=pr) will increase coverage by **<.01%**

``` diff
@@             master     #13757   diff @@
==========================================
  Files           141        141          
  Lines         51195      51196     +1   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits          43295      43296     +1   
  Misses         7900       7900          
  Partials          0          0          
```

> Powered by [Codecov](https://codecov.io?src=pr). Last update [9f94e6a...5bad8f2](https://codecov.io/gh/pydata/pandas/compare/9f94e6a04564e8269b43c5b4e83854d277ea30bd...5bad8f25a62ae8598aa3d11017d4195c37de21a7?src=pr)
 this need to address #13503 which is the main issue.
 Are you saying that if I resolve the issue in #13503 then it will also automatically address the issue in #13753? It looks like #13503 is related to how `.count()` is implemented for `.rolling`. However, in my `.expanding` example, I am using `.sum()`. It would be helpful if you could point me in the right direction or which class to make changes in. Perhaps, in `Rolling`?
 yes it's the same issue and is addressed in the same place

put tests in place first 
 pls reopen if you'd like to update
