fix extraneous output when outputting build path

[msarahan]

conda build --output was outputting other stuff, when external tools required strictly the package output path. This fixes it, and adds tests for the behavior.

Closes #949 (sorry everyone)

[stefanseefeld]

Now I see the "old" (and wrong) behavior again, i.e. it reports a label that doesn't correspond to what's in my local tree.

[msarahan]

Yeah, I was trying to be clever about avoiding downloading the source, but that just doesn't work. It will successfully render without it in your case, but it will not be accurate.

[stefanseefeld]

Now conda build ... --output again generates more output than is desirable:

(py34)[stefan@quasimodo numba]$ conda build --numpy=1.10 --python=2.7 buildscripts/condarecipe.local --output
Copying /home/stefan/projects/numba to /usr/local/Continuum/anaconda/conda-bld/work
/usr/local/Continuum/anaconda/conda-bld/linux-64/numba-0.26.0.dev-np110py27_199.tar.bz2

[codecov-io]

Current coverage is 13.0%

Merging #950 into master will increase coverage by 1.1%

@@             master       #950   diff @@
==========================================
  Files            42         42          
  Lines          5305       5313     +8   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits            632        691    +59   
+ Misses         4673       4622    -51   
  Partials          0          0          

1. 5 files (not in diff) in conda_build were modified. more
   • Misses -58
   • Hits +58

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[johanneskoester]

Can you quickly clarify when the source is downloaded now? To me, it looks like it is downloaded always, regardless of if it is needed or not. This would be a huge problem for bioconda, because we use --skip-existing and --output to determine if recipes need a rebuild. However, we have thousands of recipes in our repository and downloading the source for all of them would need ages.

[msarahan]

This isn't finished yet. The idea is that it will only download source when it needs to. For example, if your recipe uses git variables in jinja templates, you can't know the build output path without downloading the source. However, if that's not necessary, then we should not download the source.

[johanneskoester]

That's good, thanks!

[mwcraig]

Should this warning be raised even if verbose is False? I normally think of verbose as "no chatter, but if something goes wrong please do tell me."

[msarahan]

Thanks, I'll fix that.

[mwcraig]

Just one fairly minor comment. The tests do seem to be checking for #949 properly. Haven't tried running this locally, but can if you want.