gnu: guile-variant-package-name: Don’t rename ‘guile-bootstrap’.

Previously, ‘package-for-guile-2.2’ would sometimes create a variant
of (@ (gnu packages commencement) glibc-final) with a package called
“guile2.2-bootstrap” among its derivations, thereby causing an entirely
separate package graph to be built.

The reason ‘glibc-final’ would be modified despite the use of #:deep? #f is
because ‘texinfo’ depends on ‘libc-utf8-locales-for-target’, which depends on
‘glibc-final’.  This happened for ‘guile2.2-git’ because it depends on
‘texinfo’.

* gnu/packages/guile.scm (guile-variant-package-name): When ‘name’ is
“guile-bootstrap”, return it unchanged.

Change-Id: I6317927cf073085f36c4e07704469bb400b5a890
Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/packages/guile.scm

@@ -653,7 +653,10 @@ GNU@tie{}Guile.  Use the @code{(ice-9 readline)} module and call its
 (define (guile-variant-package-name prefix)
   (lambda (name)
     "Return NAME with PREFIX instead of \"guile-\", when applicable."
-    (if (string-prefix? "guile-" name)
+    (if (and (string-prefix? "guile-" name)
+
+             ;; Don't rename guile-bootstrap@2.0.
+             (not (string=? "guile-bootstrap" name)))
         (string-append prefix "-"
                        (string-drop name
                                     (string-length "guile-")))