Extract document version from git tag

Instead of hard coding the document version in the config file, use
'git describe' to get the version number from the tags and use that.
Just like before, if the version string contains a '-', then it is not
an official release and a watermark will be added to the PDF. This
catches prereleases "-pre*", untagged revisions "-g<hash>", and
uncommitted changes "-dirty".

Signed-off-by: Grant Likely <[email protected]>
Reviewed-by: Rob Herring <[email protected]>

source/conf.py

@@ -15,6 +15,7 @@
 import sys
 import os
 import time
+import subprocess
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
@@ -64,7 +65,10 @@ def setup(app):
 # built documents.
 #
 # The short X.Y version.
-version = u'0.2-pre2'
+try:
+    version = subprocess.check_output(["git", "describe", "--dirty"]).strip()
+except:
+    version = "unknown-rev"
 # The full version, including alpha/beta/rc tags.
 release = version
 
@@ -79,7 +83,7 @@ def setup(app):
 # non-false value, then it is used:
 #today = ''
 # Else, today_fmt is used as the format for a strftime call.
-today_fmt = '%d %B %Y'
+today_fmt = '%d %b %Y'
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
@@ -253,7 +257,7 @@ def setup(app):
 
 # Release numbers with a qualifier (ex. '-rc', '-pre') get a watermark.
 if '-' in release:
-    latex_elements['preamble'] = '\\usepackage{draftwatermark}\\SetWatermarkScale{.45}\\SetWatermarkText{DRAFT v%s %s}' % (release, time.strftime(today_fmt))
+    latex_elements['preamble'] = '\\usepackage{draftwatermark}\\SetWatermarkScale{.45}\\SetWatermarkText{%s}' % (release)
 
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title,