Add full Pungi version to log output

This should help with debugging by providing better information on which
Pungi version created the compose. In development, the version will show
output of git describe, in production it asks which version is installed
in site-packages/. The egg-info directory must be installed for this to
work.

It is no longer necessary to synchronize version in `setup.py` with
`pungi/__init__.py`.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

pungi/__init__.py

@@ -1 +1,24 @@
-__version__ = "4.0"
+# -*- coding: utf-8 -*-
+
+import os
+import re
+
+
+def get_full_version():
+    """
+    Find full version of Pungi: if running from git, this will return cleaned
+    output of `git describe`, otherwise it will look for installed version.
+    """
+    location = os.path.join(os.path.dirname(os.path.realpath(__file__)), '..')
+    if os.path.isdir(os.path.join(location, '.git')):
+        import subprocess
+        proc = subprocess.Popen(['git', '-C', location, 'describe', '--tags'],
+                                stdout=subprocess.PIPE)
+        output, _ = proc.communicate()
+        return re.sub(r'-1.fc\d\d?', '', output.strip().replace('pungi-', ''))
+    else:
+        import pkg_resources
+        try:
+            return pkg_resources.get_distribution('pungi').version
+        except pkg_resources.DistributionNotFound:
+            return 'unknown'