If the downloaded file is a tarfile, then decompress

Author: rjgildea

dials_data/download.py

@@ -2,6 +2,7 @@
 
 import contextlib
 import os
+import tarfile
 
 import dials_data.datasets
 from six.moves.urllib.request import urlopen
@@ -180,6 +181,12 @@ def _fetch_filelist(filelist, file_hash):
                 print("Downloading {}".format(source["url"]))
                 _download_to_file(source["url"], source["file"])
 
+                # If the file is a tar archive, then decompress
+                if tarfile.is_tarfile(source["file"]):
+                    print(f"Decompressing {source['file']}")
+                    with tarfile.open(source["file"]) as tar:
+                        tar.extractall(path=source["file"].dirname)
+
             # verify
             valid = True
             fileinfo = {