Cannot use `vc-annotate' on OS X

[Xue Fuqiao <xfq.free@gmail.com>]

Hi list,

I wanted to display an annotated version of files.el, so I pressed
`C-x v g' in that file.  But Debugger entered:

  Debugger entered--Lisp error: (file-error "Searching for program"
"No such file or directory" "bzr")
    start-process("bzr" #<buffer *Annotate files.el (rev 112804)*>
"bzr" "annotate" "--long" "--all" "-r" "112804" "files.el")
    apply(start-process "bzr" #<buffer *Annotate files.el (rev
112804)*> "bzr" ("annotate" "--long" "--all" "-r" "112804"
"files.el"))
    start-file-process("bzr" #<buffer *Annotate files.el (rev
112804)*> "bzr" "annotate" "--long" "--all" "-r" "112804" "files.el")
    apply(start-file-process "bzr" #<buffer *Annotate files.el (rev
112804)*> "bzr" ("annotate" "--long" "--all" "-r" "112804"
"files.el"))
    vc-do-command(#<buffer *Annotate files.el (rev 112804)*> async
"bzr" "/Users/xfq/emacs-repo/bzr/trunk/lisp/files.el" "annotate"
"--long" "--all" "-r" "112804")
    apply(vc-do-command #<buffer *Annotate files.el (rev 112804)*>
async "bzr" "/Users/xfq/emacs-repo/bzr/trunk/lisp/files.el" "annotate"
("--long" "--all" "-r" "112804"))
    vc-bzr-command("annotate" #<buffer *Annotate files.el (rev
112804)*> async "/Users/xfq/emacs-repo/bzr/trunk/lisp/files.el"
"--long" "--all" "-r" "112804")
    apply(vc-bzr-command "annotate" #<buffer *Annotate files.el (rev
112804)*> async "/Users/xfq/emacs-repo/bzr/trunk/lisp/files.el"
"--long" "--all" ("-r" "112804"))
    vc-bzr-annotate-command("/Users/xfq/emacs-repo/bzr/trunk/lisp/files.el"
#<buffer *Annotate files.el (rev 112804)*> "112804")
    apply(vc-bzr-annotate-command
("/Users/xfq/emacs-repo/bzr/trunk/lisp/files.el" #<buffer *Annotate
files.el (rev 112804)*> "112804"))
    vc-call-backend(Bzr annotate-command
"/Users/xfq/emacs-repo/bzr/trunk/lisp/files.el" #<buffer *Annotate
files.el (rev 112804)*> "112804")
    vc-annotate("/Users/xfq/emacs-repo/bzr/trunk/lisp/files.el" "112804" 20.0)
    call-interactively(vc-annotate nil nil)
    command-execute(vc-annotate)

I can use bzr outside Emacs, and I'm using OS X 10.8.3 with Bazaar
2.5.1 and python 2.7.2.  It seems that Emacs cannot find my bzr.  Can
anyone point me in the right direction?

FYI:
  $ which bzr
  /usr/local/bin/bzr
  $ cat /etc/paths
  /usr/bin
  /bin
  /usr/sbin
  /sbin
  /usr/local/bin

--
Best regards, Xue Fuqiao.
http://www.gnu.org/software/emacs/