title: Python's "platform.mac_ver()" reports incorrect MacOS version
body: <p>I'm using Python <a href="https://docs.python.org/3/library/platform.html" rel="noreferrer"><code>platform</code> module</a> to identify the MacOS version like this:</p>
  <pre><code>import platform
  print(platform.mac_ver())
  </code></pre>
  <p>Output:</p>
  <pre><code>In [1]: import platform
  
  In [2]: platform.mac_ver()
  Out[2]: ('10.16', ('', '', ''), 'x86_64')
  </code></pre>
  <p>I have updated to BigSur and the version is incorrect, it should be 11.0.1</p>
  <p><a href="https://i.stack.imgur.com/kgm2o.png" rel="noreferrer"><img src="https://i.stack.imgur.com/kgm2o.png" alt="enter image description here" /></a></p>
  <p>I looked at the source code of platform and it seems to parse a this file <code>/System/Library/CoreServices/SystemVersion.plist</code> to get the information.
  When reading this file from Python I get an incorrect version but from bash it is the correct one</p>
  <p>Bash:</p>
  <pre class="lang-none prettyprint-override"><code>Amirs-MacBook-Pro:~ arossert$ cat /System/Library/CoreServices/SystemVersion.plist
  &lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
  &lt;!DOCTYPE plist PUBLIC &quot;-//Apple//DTD PLIST 1.0//EN&quot; &quot;http://www.apple.com/DTDs/PropertyList-1.0.dtd&quot;&gt;
  &lt;plist version=&quot;1.0&quot;&gt;
  &lt;dict&gt;
      &lt;key&gt;ProductBuildVersion&lt;/key&gt;
      &lt;string&gt;20B50&lt;/string&gt;
      &lt;key&gt;ProductCopyright&lt;/key&gt;
      &lt;string&gt;1983-2020 Apple Inc.&lt;/string&gt;
      &lt;key&gt;ProductName&lt;/key&gt;
      &lt;string&gt;macOS&lt;/string&gt;
      &lt;key&gt;ProductUserVisibleVersion&lt;/key&gt;
      &lt;string&gt;11.0.1&lt;/string&gt;
      &lt;key&gt;ProductVersion&lt;/key&gt;
      &lt;string&gt;11.0.1&lt;/string&gt;
      &lt;key&gt;iOSSupportVersion&lt;/key&gt;
      &lt;string&gt;14.2&lt;/string&gt;
  &lt;/dict&gt;
  &lt;/plist&gt;
  </code></pre>
  <p>Python:</p>
  <pre class="lang-none prettyprint-override"><code>In [4]: print(open(&quot;/System/Library/CoreServices/SystemVersion.plist&quot;).read())
  &lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
  &lt;!DOCTYPE plist PUBLIC &quot;-//Apple//DTD PLIST 1.0//EN&quot; &quot;http://www.apple.com/DTDs/PropertyList-1.0.dtd&quot;&gt;
  &lt;plist version=&quot;1.0&quot;&gt;
  &lt;dict&gt;
      &lt;key&gt;ProductBuildVersion&lt;/key&gt;
      &lt;string&gt;20B50&lt;/string&gt;
      &lt;key&gt;ProductCopyright&lt;/key&gt;
      &lt;string&gt;1983-2020 Apple Inc.&lt;/string&gt;
      &lt;key&gt;ProductName&lt;/key&gt;
      &lt;string&gt;Mac OS X&lt;/string&gt;
      &lt;key&gt;ProductUserVisibleVersion&lt;/key&gt;
      &lt;string&gt;10.16&lt;/string&gt;
      &lt;key&gt;ProductVersion&lt;/key&gt;
      &lt;string&gt;10.16&lt;/string&gt;
      &lt;key&gt;iOSSupportVersion&lt;/key&gt;
      &lt;string&gt;14.2&lt;/string&gt;
  &lt;/dict&gt;
  &lt;/plist&gt;
  </code></pre>
  <p>What am I missing?</p>
  <p>This is the output from the same <code>ipython</code> session</p>
  <pre class="lang-none prettyprint-override"><code>In [3]: print(open(&quot;/System/Library/CoreServices/SystemVersion.plist&quot;).read())
  &lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
  &lt;!DOCTYPE plist PUBLIC &quot;-//Apple//DTD PLIST 1.0//EN&quot; &quot;http://www.apple.com/DTDs/PropertyList-1.0.dtd&quot;&gt;
  &lt;plist version=&quot;1.0&quot;&gt;
  &lt;dict&gt;
      &lt;key&gt;ProductBuildVersion&lt;/key&gt;
      &lt;string&gt;20B50&lt;/string&gt;
      &lt;key&gt;ProductCopyright&lt;/key&gt;
      &lt;string&gt;1983-2020 Apple Inc.&lt;/string&gt;
      &lt;key&gt;ProductName&lt;/key&gt;
      &lt;string&gt;Mac OS X&lt;/string&gt;
      &lt;key&gt;ProductUserVisibleVersion&lt;/key&gt;
      &lt;string&gt;10.16&lt;/string&gt;
      &lt;key&gt;ProductVersion&lt;/key&gt;
      &lt;string&gt;10.16&lt;/string&gt;
      &lt;key&gt;iOSSupportVersion&lt;/key&gt;
      &lt;string&gt;14.2&lt;/string&gt;
  &lt;/dict&gt;
  &lt;/plist&gt;
  
  
  In [4]: cat /System/Library/CoreServices/SystemVersion.plist
  &lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
  &lt;!DOCTYPE plist PUBLIC &quot;-//Apple//DTD PLIST 1.0//EN&quot; &quot;http://www.apple.com/DTDs/PropertyList-1.0.dtd&quot;&gt;
  &lt;plist version=&quot;1.0&quot;&gt;
  &lt;dict&gt;
      &lt;key&gt;ProductBuildVersion&lt;/key&gt;
      &lt;string&gt;20B50&lt;/string&gt;
      &lt;key&gt;ProductCopyright&lt;/key&gt;
      &lt;string&gt;1983-2020 Apple Inc.&lt;/string&gt;
      &lt;key&gt;ProductName&lt;/key&gt;
      &lt;string&gt;macOS&lt;/string&gt;
      &lt;key&gt;ProductUserVisibleVersion&lt;/key&gt;
      &lt;string&gt;11.0.1&lt;/string&gt;
      &lt;key&gt;ProductVersion&lt;/key&gt;
      &lt;string&gt;11.0.1&lt;/string&gt;
      &lt;key&gt;iOSSupportVersion&lt;/key&gt;
      &lt;string&gt;14.2&lt;/string&gt;
  &lt;/dict&gt;
  &lt;/plist&gt;
  </code></pre>