Fix error regarding unescape_string introduced by #8838

[dhoegh]

@tkelman I have fixed the issue mentioned in #9137.

[tkelman]

Good, looks like this fixes the problem. Can you please add a test for this problem that would fail on current master?

[dhoegh]

@tkelman I have adapted a test to test two things could you insure this is crashing on master, I do not have a nightly with it, and I do not have much time right now.

[tkelman]

Oddly this does not seem to error on master. I can experiment with things if you can suggest other ways to exercise this code path.

[dhoegh]

Thats odd because when i do the i gennerates the error:

julia> unescape_string("C:\\U \\alpha")
ERROR: \x used with no following hex digits
 in print_unescaped at string.jl:928

Which is what should be passed to the unescape at line 193, and is also coherent with what you reported.

[tkelman]

it looks like startpos is ending up as 10 for that string though, so unescape_string is only being called on \\alpha which works fine

[dhoegh]

It should not matter, I have uploaded a new with a specific test of you problem and it seem to crash on mine now.

[dhoegh]

You were right it only completes \alpha due to the startpos I’m not thinking clearly after a long day at the University.

[tkelman]

No worries, we've all been there. This fixes the error and completion of paths with spaces still works nicely, so it's good enough for me.

[tkelman]

backport now pending at #9164