store: Really disable file name canonicalization for derivation inputs.

* guix/store.scm (write-contents)[call-with-binary-input-file]: Set
  %FILE-PORT-NAME-CANONICALIZATION to #f.
* gnu/packages.scm (search-patch, search-bootstrap-binary): Leave
  %FILE-PORT-NAME-CANONICALIZATION unchanged.  This reverts 9776ebb.

gnu/packages.scm

@@ -61,14 +61,12 @@
 
 (define (search-patch file-name)
   "Search the patch FILE-NAME."
-  (with-fluids ((%file-port-name-canonicalization #f))
-    (search-path (%patch-path) file-name)))
+  (search-path (%patch-path) file-name))
 
 (define (search-bootstrap-binary file-name system)
   "Search the bootstrap binary FILE-NAME for SYSTEM."
-  (with-fluids ((%file-port-name-canonicalization #f))
-    (search-path (%bootstrap-binaries-path)
-                 (string-append system "/" file-name))))
+  (search-path (%bootstrap-binaries-path)
+               (string-append system "/" file-name)))
 
 (define %distro-module-directory
   ;; Absolute path of the (gnu packages ...) module root.

guix/store.scm

@@ -238,12 +238,14 @@
   "Write SIZE bytes from FILE to output port P."
   (define (call-with-binary-input-file file proc)
     ;; Open FILE as a binary file.  This avoids scan-for-encoding, and thus
-    ;; avoids any initial buffering.
-    (let ((port (open-file file "rb")))
-      (catch #t (cut proc port)
-        (lambda args
-          (close-port port)
-          (apply throw args)))))
+    ;; avoids any initial buffering.  Disable file name canonicalization to
+    ;; avoid stat'ing like crazy.
+    (with-fluids ((%file-port-name-canonicalization #f))
+      (let ((port (open-file file "rb")))
+        (catch #t (cut proc port)
+          (lambda args
+            (close-port port)
+            (apply throw args))))))
 
   (define (dump in size)
     (define buf-size 65536)