Only add the git version if building on github, as it causes a rebuil…

…d everytime sphinx build is called.

conf.py

@@ -24,9 +24,6 @@
 copyright = '2022-2024, Jason K. Moore'
 author = 'Jason K. Moore'
 version = '0.2.dev0'
-commit_id = subprocess.check_output(['git', 'rev-parse', '--short',
-                                     'HEAD']).strip().decode('ascii')
-version += '+' + commit_id
 
 # -- General configuration ---------------------------------------------------
 
@@ -54,6 +51,11 @@
 
 ONGITHUB = "ONGITHUB" in os.environ
 
+if ONGITHUB:
+    commit_id = subprocess.check_output(['git', 'rev-parse', '--short',
+                                         'HEAD']).strip().decode('ascii')
+    version += '+' + commit_id
+
 if not ONGITHUB:
     # Display TODO notes.
     todo_include_todos = True