Error on installed qt-4 package

[Andreas Enge <andreas@enge.fr>]

The following transcript shows a problem I have trouble understanding; I can
build qt-4 with ./preinst-env, but not after installation (on git-1e9ed0e3):

$ rm -rf ~/.cache
$ rm -rf /usr/local/guix-git/share
$ make install
$ guix package -A qt
qt      4.8.5   out     gnu/packages/qt.scm:67:2
qt      5.1.1   out     gnu/packages/qt.scm:67:2
$ guix build qt
substitute-binary: ;;; note: source file /usr/local/guix-git/bin/guix
substitute-binary: ;;;       newer than compiled /root/.cache/guile/ccache/2.0-LE-8-2.0/usr/local/guix-git/bin/guix.go
/nix/store/j6s7d1cf5b0q97yp31y6lfkagh941d35-qt-5.1.1
$ guix build qt-5.1.1
substitute-binary: ;;; note: source file /usr/local/guix-git/bin/guix
substitute-binary: ;;;       newer than compiled /root/.cache/guile/ccache/2.0-LE-8-2.0/usr/local/guix-git/bin/guix.go
/nix/store/j6s7d1cf5b0q97yp31y6lfkagh941d35-qt-5.1.1
$ ./pre-inst-env guix build qt-4.8.5
;;; note: source file /home/privat/Programme/guix/gnu/packages/gnuzilla.scm
;;;       newer than compiled /home/privat/Programme/guix/gnu/packages/gnuzilla.go
substitute-binary: ;;; note: source file /usr/local/guix-git/bin/guix
substitute-binary: ;;;       newer than compiled /root/.cache/guile/ccache/2.0-LE-8-2.0/usr/local/guix-git/bin/guix.go
/nix/store/z70fv39wa8yrvvqq9zfidsh86z72p4gr-qt-4.8.5
$ guix build qt-4.8.5
Backtrace:
In ice-9/boot-9.scm:
  63: 19 [call-with-prompt prompt0 ...]
In ice-9/eval.scm:
 407: 18 [eval # #]
In ice-9/boot-9.scm:
2111: 17 [save-module-excursion #<procedure 11f0100 at ice-9/boot-9.scm:3646:3 ()>]
3651: 16 [#<procedure 11f0100 at ice-9/boot-9.scm:3646:3 ()>]
1380: 15 [%start-stack load-stack ...]
1385: 14 [#<procedure 12509c0 ()>]
In unknown file:
   ?: 13 [primitive-load "/usr/local/bin/guix"]
In guix/ui.scm:
 544: 12 [run-guix-command build "qt-4.8.5"]
In ice-9/boot-9.scm:
 149: 11 [catch srfi-34 #<procedure 17ceb60 at guix/ui.scm:157:2 ()> ...]
 157: 10 [#<procedure 1716690 ()>]
 149: 9 [catch system-error ...]
 157: 8 [#<procedure 1716640 ()>]
In guix/scripts/build.scm:
 246: 7 [#<procedure 1728720 at guix/scripts/build.scm:237:2 ()>]
In srfi/srfi-1.scm:
 664: 6 [filter-map #<procedure 1730cc0 at guix/scripts/build.scm:248:33 (expr)> #]
In guix/packages.scm:
 432: 5 [cache # "x86_64-linux" #<procedure thunk ()>]
 522: 4 [thunk]
 295: 3 [patch-and-repack # # # ...]
In srfi/srfi-1.scm:
 601: 2 [map #<procedure 3b01e80 at guix/packages.scm:295:9 (number patch)> (0) ...]
In guix/packages.scm:
 297: 1 [#<procedure 3b01e80 at guix/packages.scm:295:9 (number patch)> 0 #f]
In unknown file:
   ?: 0 [basename #f #<undefined>]

ERROR: In procedure basename:
ERROR: In procedure basename: Wrong type argument in position 1 (expecting string): #f

I made a "make clean; make install" without effect. Is there a subtle error
in my qt-4 package?

Also, I am a bit surprised by these textual references to cached files in
/root, as I am running guix as a normal user and install into a normal user-
owned directory.

Andreas