loading virtualenv if we install mercurial

bin/compile

@@ -115,6 +115,7 @@ fi
 
 if (grep -Fiq "hg+" requirements.txt) then
   PIP_DOWNLOAD_CACHE=$PIP_DOWNLOAD_CACHE bin/pip install --use-mirrors mercurial | indent
+  source bin/activate
 fi
 
 echo "-----> Installing dependencies using pip version $(bin/pip --version | awk '{print $2}')"