Remove exception for experimental-build branch

It was replaced with using feature branches, which are easier
to keep track of.

master_unpack.py

@@ -98,8 +98,6 @@ class Package:
 def get_download_dir(branch):
     if not branch or branch == 'master':
         directory = DOWNLOAD_DIR
-    elif branch == 'experimental-build':
-        directory = os.path.join(DOWNLOAD_DIR, "experimental")
     else:
         directory = os.path.join(DOWNLOAD_DIR, branch)
         os.makedirs(directory, exist_ok=True)