Fix doc build if git is absent

When building packages if git is absent, then we should not set
html_last_updated_fmt. It can still be set via the -D switch
when building with sphinx-build.

Change-Id: Ibbfb81955e5e68553af551baeb17d4facd988e5c
Closes-Bug: #1552251

1 files changed, 10 insertions, 5 deletions

diff --git a/doc/source/conf.py b/doc/source/conf.py
index fcc3ecd2..e5f6d731 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -6,6 +6,7 @@ import sys
 import os
 import fileinput
 import fnmatch
+import warnings
 
 BASE_DIR = os.path.dirname(os.path.abspath(__file__))
 ROOT = os.path.abspath(os.path.join(BASE_DIR, "..", ".."))
@@ -77,11 +78,15 @@ pygments_style = 'sphinx'
 # Output file base name for HTML help builder.
 htmlhelp_basename = '%sdoc' % project
 
-git_cmd = ["git", "log", "--pretty=format:'%ad, commit %h'", "--date=local",
-   "-n1"]
-html_last_updated_fmt = subprocess.Popen(git_cmd,
-                                         stdout=subprocess.PIPE).\
-                                         communicate()[0]
+try:
+    git_cmd = ["git", "log", "--pretty=format:'%ad, commit %h'", "--date=local",
+               "-n1"]
+    html_last_updated_fmt = subprocess.Popen(git_cmd,
+                                             stdout=subprocess.PIPE).\
+                                             communicate()[0]
+except Exception:
+    warnings.warn('Cannot get last updated time from git repository. '
+                  'Not setting "html_last_updated_fmt".')
 
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title, author, documentclass