Link 'source' to commit of the selected version

doc/conf.py

@@ -186,6 +186,7 @@ htmlhelp_basename = 'theanodoc'
 # Options for the linkcode extension
 # ----------------------------------
 # Resolve function
+# This function is used to populate the (source) links in the API
 def linkcode_resolve(domain, info):
     def find_source():
         # try to find the file and line number, based on code from numpy:
@@ -206,7 +207,10 @@ def linkcode_resolve(domain, info):
         filename = 'theano/%s#L%d-L%d' % find_source()
     except Exception:
         filename = info['module'].replace('.', '/') + '.py'
-    tag = 'master' if 'dev' in release else ('v' + release)
+    import subprocess
+    tag = subprocess.Popen(['git', 'rev-parse', 'HEAD'],
+                           stdout=subprocess.PIPE,
+                           universal_newlines=True).communicate()[0][:-1]
     return "https://github.com/Theano/theano/blob/%s/%s" % (tag, filename)
 
 # Options for LaTeX output