Use of numbers in backquoted identifiers results in unintelligible repl errors

[scabug]

scala> val `1 + 1` = 1 + 1
<console>:5: error: Invalid literal number
  lazy val $result = 1$u0020$plus$u00201
                                                                         ^
<console>:10: error: Invalid literal number
 + "1 + 1: Int = " + scala.runtime.ScalaRunTime.replStringOf(1$u0020$plus$u00201, 1000)
                                                                                                                 ^
<console>:13: error: ')' expected but '}' found.
  }
  ^

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-8456?orig=1
Reporter: @densh
Affected Versions: 2.11.0-RC4

[scabug]

@densh said:
This issues seems to be localized to the REPL. It works just fine if you put into a regular file and compile it.

[scabug]

Li Haoyi (lihaoyi) said:
This has been fixed in the Ammonite REPL.

@  val `1 + 1` = 1 + 1
`1 + 1`: Int = 2
@ `1 + 1`
res31: Int = 2
@

[SethTisue]

still reproducible in 2.13.2