[BUG] banned_strings issue with some strings containing ASCII period

[mfiano]

OS

Linux

GPU Library

CUDA 12.x

Python version

3.12

Describe the bug

banned_strings=[] OK
banned_strings=["."] OK
banned_strings=[".."] OK
banned_strings=["..."] breaks
banned_strings=[".foo."] breaks
banned_strings=["---"] OK

It seems that any literal string of at least 3 characters which includes a . at in position 0 corrupts the model's output (usually just emitting the stop token, but sometimes gibberish or an incomplete message).

Reproduction steps

Pass banned_strings="..." for a simple reproduction.

I tested with EXL3 and Mistral-Small 24B.

Expected behavior

Expected behavior would be for literal strings to match verbatim instead of getting confused with regex or backtracking.

Logs

No response

Additional context

No response

Acknowledgements

• I have looked for similar issues before submitting this one.
• I have read the disclaimer, and this issue is related to a code bug. If I have a question, I will use the Discord server.
• I understand that the developers have lives and my issue will be answered when possible.
• I understand the developers of this program are human, and I will ask my questions politely.