Fix issue #118

[sallyruthstruik]

Fixed error described in #118

[codecov-io]

Codecov Report

Merging #325 into master will increase coverage by 0.06%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #325      +/-   ##
==========================================
+ Coverage   75.32%   75.38%   +0.06%     
==========================================
  Files          11       11              
  Lines        1552     1552              
==========================================
+ Hits         1169     1170       +1     
+ Misses        383      382       -1

Impacted Files	Coverage Δ
storages/backends/sftpstorage.py	86.84% <100%> (+0.65%)	⬆️

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[jschneier]

Thanks for your contribution! This looks good although I sort of itch to want to remove this auto-adding at all.

[jschneier]

Note that there is a minor functionality change where a non-existent file could have been passed in and we'd fall back. I count that as a bug anyway so no big deal.

[sallyruthstruik]

I found critical bug: when $HOME/.ssh/known hosts exists, whatever None is passed in load_known_hosts. Fixed in this PR: #330