BF: Don't discover directory as procedure

[bpoldrack]

Closes #3792

We used to discover a directory at the configured procedure location as an actual procedure based on its executable flag.

[codecov]

Codecov Report

Merging #3793 into master will increase coverage by 0.06%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3793      +/-   ##
==========================================
+ Coverage   80.68%   80.75%   +0.06%     
==========================================
  Files         273      273              
  Lines       35917    35918       +1     
==========================================
+ Hits        28981    29004      +23     
+ Misses       6936     6914      -22

Impacted Files	Coverage Δ
datalad/interface/run_procedure.py	86.33% <100%> (+19.25%)	⬆️
datalad/interface/tests/test_run_procedure.py	100% <100%> (ø)	⬆️
datalad/downloaders/tests/test_http.py	58.08% <0%> (-2.21%)	⬇️

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[kyleam]

Thanks. Looks obviously correct.

I had the thought that it'd be a little more natural to filter out directories upstream and not pass them as the script_file argument to _guess_exec, but looking at the code the spot you chose does seem the most straightforward spot to tack this on.

This patch applies cleanly to 0.11.x, so it'd be good for it to go there. I'm going to push a rebased branch to scratch/bf-discover-procedures in order to trigger tests. That way, if you agree with this going to 0.11.x, hopefully you won't have to wait for another test cycle and can just reset to scratch/bf-discover-procedures and then do the merge into 0.11.x then master.

Here's the travis build triggered by that:
https://travis-ci.org/datalad/datalad/builds/599404967

[bpoldrack]

Thanks, @kyleam

[bpoldrack]

And yes, I also initially thought it should be a different spot, but that's the way it's build.