`clean ns` removes referred Greek letter symbols

[klausharbo]

Issue

If I refer to symbols consisting of Greek letters in the ns declaration clj-refactor removes them when doing clean ns or add missing libspec.

Expected behavior

Symbols in non-Latin scripts (in the example below: Greek and Danish) treated the same as those consisting of letters from ASCII.

Actual behavior

The symbols are removed from :refer part of the libspec.

Steps to reproduce the problem

src/ns1.clj:

(ns ns1)

(def A inc)
(def Γ inc)
(def Å inc)

src/ns2.clj:

(ns ns2
  (:require [ns1 :refer [A Γ Å]]))

(defn myfun []
  (+ (A 1) (Γ 2) (Å 3)))

The Γ and Å are code points #x393 and #xc5 respectively.

After evaluating cljr-clean-ns in buffer ns2.clj the buffer contains

(ns ns2
  (:require [ns1 :refer [A]]))

(defn myfun []
  (+ (A 1) (Γ 2) (Å 3)))

which will not compile.

Environment & Version information

clj-refactor.el version information

clj-refactor 2.5.0-SNAPSHOT (package: 20190618.716), refactor-nrepl 2.5.0-SNAPSHOT

CIDER version information

;; CIDER 0.24.0snapshot (package: 20191103.1528), nREPL 0.6.0
;; Clojure 1.10.1, Java 1.8.0_192

Leiningen or Boot version

Leiningen 2.9.0 on Java 1.8.0_192 OpenJDK 64-Bit Server VM

Emacs version

GNU Emacs 26.3 (build 1, x86_64-apple-darwin18.7.0, Carbon Version 158 AppKit 1671.6) of 2019-10-04

Operating system

Darwin locke.local 19.0.0 Darwin Kernel Version 19.0.0: Thu Oct 17 16:17:15 PDT 2019; root:xnu-6153.41.3~29/RELEASE_X86_64 x86_64

[vemv]

We should work on this one at some point.

Today I found a possibly related issue #540