build: Support running the test suite from a directory with symlinks.

Fixes <http://bugs.gnu.org/17935>.
Reported by Alex Kost <alezost@gmail.com>.

* test-env.in: Canonicalize $NIX_STORE_DIR, and remove
  $NIX_IGNORE_SYMLINK_STORE setting.
* tests/guix-register.sh: Likewise, canonicalize $new_store_dir and
  $new_store and leave $NIX_IGNORE_SYMLINK_STORE unchanged.

test-env.in

@@ -27,8 +27,15 @@
 if [ -x "@abs_top_builddir@/guix-daemon" ]
 then
     NIX_SETUID_HELPER="@abs_top_builddir@/nix-setuid-helper" # normally unused
-    NIX_IGNORE_SYMLINK_STORE=1	# in case the store is a symlink
     NIX_STORE_DIR="@GUIX_TEST_ROOT@/store"
+
+    # Do that because store.scm calls `canonicalize-path' on it.
+    mkdir -p "$NIX_STORE_DIR"
+
+    # Canonicalize the store directory name in an attempt to avoid symlinks in
+    # it or its parent directories.  See <http://bugs.gnu.org/17935>.
+    NIX_STORE_DIR="`cd "@GUIX_TEST_ROOT@/store"; pwd -P`"
+
     NIX_LOCALSTATE_DIR="@GUIX_TEST_ROOT@/var"
     NIX_LOG_DIR="@GUIX_TEST_ROOT@/var/log/guix"
     NIX_DB_DIR="@GUIX_TEST_ROOT@/db"
@@ -71,9 +78,6 @@ then
         GUIX_ALLOW_UNAUTHENTICATED_SUBSTITUTES				\
         NIX_CONF_DIR XDG_CACHE_HOME
 
-    # Do that because store.scm calls `canonicalize-path' on it.
-    mkdir -p "$NIX_STORE_DIR"
-
     # Launch the daemon without chroot support because is may be
     # unavailable, for instance if we're not running as root.
     "@abs_top_builddir@/pre-inst-env"				\

tests/guix-register.sh

@@ -57,8 +57,8 @@ guile -c "
 #
 
 mkdir -p "$new_store/$storedir"
-new_store_dir="`cd "$new_store/$storedir" ; pwd`"
-new_store="`cd "$new_store" ; pwd`"
+new_store_dir="`cd "$new_store/$storedir" ; pwd -P`"
+new_store="`cd "$new_store" ; pwd -P`"
 
 to_copy="`guix build guile-bootstrap`"
 cp -r "$to_copy" "$new_store_dir"
@@ -81,7 +81,6 @@ guix-register --prefix "$new_store" "$closure"
 
 # Now make sure this is recognized as valid.
 
-NIX_IGNORE_SYMLINK_STORE=1
 NIX_STORE_DIR="$new_store_dir"
 NIX_STATE_DIR="$new_store$localstatedir"
 NIX_LOG_DIR="$new_store$localstatedir/log/guix"