title: can't copy 'ANIFEST.in': doesn't exist or not a regular file
body: <p><strong><em>NOTE:</em></strong> As of Sep. 4th, 2015, I can no longer reproduce this problem, using current versions of python and setuptools/distutils, in either python 2 or 3.</p>
  
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  <p><em>NOTE</em>: I've answered this question myself and will be accepting the answer as soon as the system lets me, but this would appear to be the only instance of an English-language reference to the problem on the internet (according to google), so I thought I'd post both in hopes this can be useful.</p>
  
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  <p>I ran into a problem that I found impossible to debug when installing a python package of my own.  It's a very simple package, with a flat structure (no subdirectories), and a few data files I need copied over at installation.  With a few deletions for brevity, I have this:</p>
  
  <pre><code>spherical_functions
  ├── MANIFEST.in
  ├── __init__.py
  ├── spherical_functions.py
  ├── ladder_operator_coefficients.npy
  └── setup.py
  </code></pre>
  
  <p>When installing from my source directory, I have no problems.  But when I either switched to <code>setuptools</code> or installed with <code>pip</code> (which is needed for distribution), I get the error</p>
  
  <pre><code>can't copy 'ANIFEST.in': doesn't exist or not a regular file
  </code></pre>
  
  <p>Note the missing <code>M</code> at the beginning of that file name.  I hacked into <code>distutils</code> a bit to verify that it was actually trying to copy <code>ANIFEST.in</code>, rather than just misreporting the name.  Unfortunately, the trail ends there, because the rest of the setuptools code is hidden in some egg I don't understand.</p>
  
  <p>A similar problem arises without a <code>MANIFEST.in</code> file, using just the <code>package_data</code> option to the <code>setup</code> function, where it misses the first letter of the data file, as in</p>
  
  <pre><code>error: can't copy 'adder_operator_coefficients.npy': doesn't exist or not a regular file
  </code></pre>