Handle python option to read program from stdin when rewriting arguments to attach to subprocess

[guyingzhao]

it's ok to execute via pydev run but failed via pydev debug, see:

pypa/virtualenv#1423

I think the fix may be restoring old sys.argv after rewritting command line

[fabioz]

It's probably trickier than that... the issue is that the option python - is not properly supported to automatically attach to subprocesses (python itself would read the stdin contents to execute that file).

i.e.: Output from python help:
- : program read from stdin (default; interactive mode if a tty)

So, if - is passed, pydevd needs to recognize that this option is passed to the python interpreter and do the same work it'd do after having the debugger setup in the subprocess.

[guyingzhao]

Yes, it's tricker :).

I have fixed this locally by modify virtualenv.py and perhaps I will look for alternative way to resolve this later.