Improve borg process spawning and result checking

backup.py

@@ -9,6 +9,7 @@ import os
 import re
 import sys
 import stat
+import time
 import pathlib
 import subprocess
 
@@ -254,9 +255,19 @@ def main(argv: list[str]):
                                 stdin=subprocess.PIPE)
         if borg.stdin is None:
             raise Exception("no pipe")
-        backup.run(borg.stdin)
-        borg.stdin.close()
-        ret = borg.wait()
+        try:
+            # Give borg some time to start, just to clean up stdout
+            time.sleep(2)
+            backup.run(borg.stdin)
+        except BrokenPipeError:
+            sys.stderr.write(f"broken pipe\n")
+        finally:
+            try:
+                borg.stdin.close()
+            except BrokenPipeError:
+                pass
+            borg.wait()
+        ret = borg.returncode
         if ret < 0:
             sys.stderr.write(f"error: process exited with signal {-ret}\n")
             return 1