gnu: emacs-sly: Update to 20210105 (fixes breaking issues).

* gnu/packages/emacs-xyz.scm (emacs-sly): Update to 20210105.

gnu/packages/emacs-xyz.scm

@@ -9531,19 +9531,22 @@ CIDER).")
 
 (define-public emacs-sly
   ;; Update together with sbcl-slynk.
+  (let ((commit "dffdf3caa12e964127d6eb45ba92ac0442cc5a48"))
+    ;; Latest stable 1.0.42 is broken:
+    ;; https://github.com/joaotavora/sly/issues/394.
     (package
       (name "emacs-sly")
-    (version "1.0.42")
+      (version (git-version "1.0.42" "1" commit))
       (source
        (origin
          (method git-fetch)
          (uri (git-reference
                (url "https://github.com/joaotavora/sly")
-             (commit version)))
+               (commit commit)))
          (file-name (git-file-name name version))
          (sha256
           (base32
-         "10l867c4hgcpiajcfkz9g9vabp7y4bcgy51la6n9pqxrlg1fs455"))))
+           "0vv185gz3rkfng5y79dijfnc11p92qdz2kdza05avjbpqfs6l0zn"))))
       (build-system emacs-build-system)
       (native-inputs
        `(("texinfo" ,texinfo)))
@@ -9604,7 +9607,7 @@ highlight the object and remain stable throughout the REPL session;
 
 SLY tracks SLIME's bugfixes and all its familiar features (debugger, inspector,
 xref, etc.) are still available, but with better integration.")
-    (license license:gpl3+)))
+      (license license:gpl3+))))
 
 (define-public emacs-sly-quicklisp
   (let ((commit "01ebe3976a244309f2e277c09206831135a0b66c")