Rewrite zip archive creation (#389)

This reimplements the functionality of `shutil.make_archive` without
the need for calls to `os.chdir`. This is thread-safe, and fixes the
issues we've been seeing with finished build showing console output
for other builds.

It will also hopefully fix the occasional zip file creation issues
we've been seeing.

app/util/fs.py

@@ -2,6 +2,7 @@
 import shutil
 import tarfile
 import tempfile
+import zipfile
 
 from app.util.process_utils import Popen_with_delayed_expansion
 
@@ -131,9 +132,17 @@ def zip_directory(target_dir: str, archive_filename: str) -> str:
     """
     # Create the archive in a temp location and then move it to the target dir.
     # (Otherwise the resulting archive will include an extra zero-byte file.)
-    tmp_path = shutil.make_archive(tempfile.mktemp(), 'zip', target_dir)
     target_path = os.path.join(target_dir, archive_filename)
-    shutil.move(tmp_path, target_path)
+    with tempfile.TemporaryDirectory() as temp_dirpath:
+        tmp_zip_filename = os.path.join(temp_dirpath, 'clusterrunner_tmp__' + archive_filename)
+        with zipfile.ZipFile(tmp_zip_filename, 'w', compression=zipfile.ZIP_DEFLATED) as zf:
+            for dirpath, dirnames, filenames in os.walk(target_dir):
+                for filename in filenames:
+                    path = os.path.normpath(os.path.join(dirpath, filename))
+                    if os.path.isfile(path):
+                        relpath = os.path.relpath(path, target_dir)
+                        zf.write(path, relpath)
+        shutil.move(tmp_zip_filename, target_path)
     return target_path