Update Python package to use the version from the git tag.

MANIFEST.in

@@ -0,0 +1 @@
+include version.py

setup.py

@@ -1,9 +1,10 @@
 #!/usr/bin/env python
 
 from setuptools import setup
+import version
 
 setup(name='riak_pb',
-      version='2.0.0.7',
+      version=version.get_version(),
       description='Riak Protocol Buffers Messages',
       packages=['riak_pb'],
       requires=['protobuf(==2.4.1)'],

version.py

@@ -0,0 +1,89 @@
+# This program is placed into the public domain.
+
+"""
+Gets the current version number.
+If in a git repository, it is the current git tag.
+Otherwise it is the one contained in the PKG-INFO file.
+
+To use this script, simply import it in your setup.py file
+and use the results of get_version() as your package version:
+
+    from version import *
+
+    setup(
+        ...
+        version=get_version(),
+        ...
+    )
+"""
+
+__all__ = ('get_version')
+
+from os.path import dirname, isdir, join
+import re
+from subprocess import CalledProcessError, Popen, PIPE
+
+try:
+    from subprocess import check_output
+except ImportError:
+    def check_output(*popenargs, **kwargs):
+        r"""Run command with arguments and return its output as a byte string.
+
+        If the exit code was non-zero it raises a CalledProcessError.  The
+        CalledProcessError object will have the return code in the returncode
+        attribute and output in the output attribute.
+
+        The arguments are the same as for the Popen constructor.  Example:
+
+        >>> check_output(["ls", "-l", "/dev/null"])
+        'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null\n'
+
+        The stdout argument is not allowed as it is used internally.
+        To capture standard error in the result, use stderr=STDOUT.
+
+        >>> check_output(["/bin/sh", "-c",
+        ...               "ls -l non_existent_file ; exit 0"],
+        ...              stderr=STDOUT)
+        'ls: non_existent_file: No such file or directory\n'
+        """
+        if 'stdout' in kwargs:
+            raise ValueError('stdout argument not allowed, it will be overridden.')
+        process = Popen(stdout=PIPE, *popenargs, **kwargs)
+        output, unused_err = process.communicate()
+        retcode = process.poll()
+        if retcode:
+            cmd = kwargs.get("args")
+            if cmd is None:
+                cmd = popenargs[0]
+            raise CalledProcessError(retcode, cmd, output=output)
+        return output
+
+version_re = re.compile('^Version: (.+)$', re.M)
+
+
+def get_version():
+    d = dirname(__file__)
+
+    if isdir(join(d, '.git')):
+        # Get the version using "git describe".
+        cmd = 'git describe --tags --match [0-9]*'.split()
+        try:
+            version = check_output(cmd).decode().strip()
+        except CalledProcessError:
+            print('Unable to get version number from git tags')
+            exit(1)
+
+        # PEP 386 compatibility
+        if '-' in version:
+            version = '.post'.join(version.split('-')[:2])
+
+    else:
+        # Extract the version from the PKG-INFO file.
+        with open(join(d, 'PKG-INFO')) as f:
+            version = version_re.search(f.read()).group(1)
+
+    return version
+
+
+if __name__ == '__main__':
+    print(get_version())