Use shell instead of gitpython

publish_images.py

@@ -4,16 +4,22 @@ import subprocess as sp
 import sys
 import time
 
-import git
-
 REGISTRY_URL = 'docker.km3net.de'
 
 
+def get_changed_dockerfiles():
+    """Checks the last Git commit and returns a list of changed Dockefiles"""
+    diff_cmd = "git diff-tree --no-commit-id --name-only -r HEAD"
+    child = sp.Popen(diff_cmd, shell=True, stdout=sp.PIPE, stderr=sp.PIPE)
+    out, _ = child.communicate()
+
+    changed_files = [l.decode().rstrip() for l in out.split(b'\n')]
+    changed_dockerfiles = [f for f in changed_files if f.startswith("base/")]
+    return changed_dockerfiles
+
+
 def main():
-    changed_dockerfiles = [
-        f.a_path for f in git.Repo('.').index.diff("HEAD~1")
-        if f.a_path.startswith("base/")
-    ]
+    changed_dockerfiles = get_changed_dockerfiles()
     n_files = len(changed_dockerfiles)
 
     if n_files == 0: