utf-8 codec error about p4transfer HOT 6 OPEN

2023-10-14 15:29:13,115:P4Transfer:DEBUG: filelogs count: 2369
2023-10-14 15:29:13,117:P4Transfer:DEBUG: src('sync', '//<REMOVEDWSNAME>/...@=54236')
2023-10-14 15:29:13,176:P4Transfer:WARNING: src:sync-msg, //<REMOVEDWSNAME>//...@=54236 - file(s) up-to-date.
2023-10-14 15:29:13,176:P4Transfer:DEBUG: src[]
2023-10-14 15:29:13,187:P4Transfer:ERROR: 'utf-8' codec can't decode byte 0x96 in position 9489: invalid start byte
Traceback (most recent call last):
  File "/opt/p4transfer/p4transfer/P4Transfer.py", line 2632, in replicate
    num_changes = self.replicate_changes()
  File "/opt/p4transfer/p4transfer/P4Transfer.py", line 2448, in replicate_changes
    fileRevs, specialMoveRevs, srcFileLogs = self.source.getChange(change['change'])
  File "/opt/p4transfer/p4transfer/P4Transfer.py", line 1291, in getChange
    chRev.updateDigest()
  File "/opt/p4transfer/p4transfer/P4Transfer.py", line 626, in updateDigest
    self.fileSize, self.digest = getKTextDigest(self.fixedLocalFile)
  File "/opt/p4transfer/p4transfer/P4Transfer.py", line 521, in getKTextDigest
    contents = contents.decode()
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x96 in position 9489: invalid start byte

root@perforce:/opt/p4transfer# file -bi  /opt/p4transfer/transfers/<REMOVED>
text/plain; charset=unknown-8bit

$ grep -n "open(" p4transfer/P4Transfer.py 
469:    with open(fname, flags) as fh:
479:    with open(fname, flags) as fh:
504:    with open(fname, "rb") as f:
2210:            with open(fpath, "a") as fh:
2232:        with open(fpath, "a") as fh:
2316:            with open(self.options.config) as f:

$ diff -u P4Transfer.py P4Transfer.py.modified.py 
--- P4Transfer.py	2023-09-21 16:31:03.163049658 +0000
+++ P4Transfer.py.modified.py	2023-10-14 21:50:24.936233459 +0000
@@ -518,12 +518,12 @@
     "Special calculation for ktext files - ignores lines with keywords in them"
     contents = readContents(fname)
     if python3:
-        contents = contents.decode()
+        contents = contents.decode(errors='surrogateescape')
     m = hashlib.md5()
     # Optimisation to search on whole file
     if not re_rcs_keywords.search(contents):
         if python3:
-            m.update(contents.encode())
+            m.update(contents.encode(errors='surrogateescape'))
         else:
             m.update(contents)
         fileSize = os.path.getsize(fname)
@@ -533,7 +533,7 @@
     for line in lines:
         if not re_rcs_keywords.search(line):
             if python3:
-                m.update(line.encode())
+                m.update(line.encode(errors='surrogateescape'))
             else:
                 m.update(line)
             fileSize += len(line)