Issues with autocompletion of backtick-delimited identifiers in the REPL

[scabug]

This is a very minor issue.

If we define the following in the REPL

object Foo { val `1 ?` = () }

and we type:

Foo.<tab>

then "1 ?" is suggested as an option.
If we type:

Foo.1<tab>

then this autocompletes to

Foo.1 ?

which isn't valid, so ought to complete to

Foo.`1 ?`

Interestingly,

Foo.`<tab>

will suggest all members of Foo correctly, though (for example),

Foo.`c<tab>

appears to search the global namespace, offering suggestions such as classOf, clone, com and collection.

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-6919?orig=1
Reporter: @propensive
Affected Versions: 2.10.0
See #7957

[scabug]

@retronym said:
I tried to implement this as part of my recent REPL revamp. See the last commit scala/scala@2.11.x...retronym:ticket/6919

Still needs quite a bit more finesse.

[som-snytt]

Should also backtick keywords, per linked ticket.