fix: pre-write SVN password to stdin to avoid deadlock on prompt

svn_mirror/mirror.py

@@ -232,13 +232,16 @@ class Mirror:
             text=True,
         )
 
+        # git svn prompts for password on stderr (no newline) and reads from
+        # stdin.  Write password immediately so it's buffered for the prompt.
+        if password:
+            process.stdin.write(password + "\n")
+            process.stdin.flush()
+
         for line in process.stdout or []:
             line = line.rstrip()
             if line:
                 logger.info("[git svn] %s", line)
-            if "Password for" in line and password:
-                process.stdin.write(password + "\n")
-                process.stdin.flush()
 
         ret = process.wait()
         if ret != 0: