IndexError: too many indices for tensor of dimension 1

[guo560]

Describe the bug(问题描述)

在basemodel的fit函数中，若batch_size为1，且model为多任务模型时，会导致y_pred的第0个维度被丢弃，从而产生错误。

[shenweichen]

Thanks for reporting this. I prepared a fix in PR #310.

What changed:

• avoid unsafe global squeeze() in BaseModel.fit for multi-task outputs
• keep MMOE/PLE expert-gating shape-safe with squeeze(1)
• add regression tests for batch_size=1 multi-task training paths

PR: #310