[SPARK-12132] [PYSPARK] raise KeyboardInterrupt inside SIGINT handler

[davies]

Currently, the current line is not cleared by Cltr-C

After this patch

>>> asdfasdf^C
Traceback (most recent call last):
  File "~/spark/python/pyspark/context.py", line 225, in signal_handler
    raise KeyboardInterrupt()
KeyboardInterrupt

It's still worse than 1.5 (and before).

[mkman84]

Thanks @davies ! It is indeed still worse than 1.5, since it didn't throw the traceback in, but at least it's better than having to delete everything on the current line or worse, hit enter and accidentally execute some code in the shell that wasn't intended! Perhaps that can just be cleaned up in 1.6.1? Or I'll just look into a clean way to fix this

[SparkQA]

Test build #47154 has finished for PR 10134 at commit fd9cd0d.

• This patch fails from timeout after a configured wait of 250m.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #2166 has finished for PR 10134 at commit fd9cd0d.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):\n * class CrossValidator @Since(\"1.2.0\") (@Since(\"1.4.0\") override val uid: String)\n * class ParamGridBuilder @Since(\"1.2.0\")\n * class TrainValidationSplit @Since(\"1.5.0\") (@Since(\"1.5.0\") override val uid: String)\n