=== Steps ===
i. I downloaded http://ftp.gnu.org/gnu/emacs/windows/emacs-24.5-bin-i686-mingw32.zip.
ii. I extracted zip file to temp folder; completely unmodified.
iii. I opened an MSYS shell and cd'd into the temp/bin folder.
iv. I ran ./emacs.exe -Q.
v. I C-x C-f and call the new file temp.py
vi. I type the following up UNTIL % - which represents the cursor position:
import re as myre
var = [
%
vii. I then press TAB and get the minibuffer message: Wrong type argument: number-or-marker-p, nil
=== END Steps ===

In GNU Emacs 24.5.1 (i686-pc-mingw32)
of 2015-04-11 on LEG570
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
`configure --prefix=/c/usr --host=i686-pc-mingw32'

Important settings:
  value of $LANG: ENG
  locale-coding-system: cp1252

Major mode: Python

Minor modes in effect:
  tooltip-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Quit
temp.py has auto save data; consider M-x recover-this-file
Can't guess python-indent-offset, using defaults: 4
python-indent--calculate-indentation: Wrong type argument: number-or-marker-p, nil [2 times]
Quit
Making completion list... [2 times]

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils help-mode help-fns python easymenu json comint
ring cl-loaddefs cl-lib ansi-color time-date tooltip electric uniquify
ediff-hook vc-hooks lisp-float-type mwheel dos-w32 ls-lisp
w32-common-fns disp-table w32-win w32-vars tool-bar dnd fontset image
regexp-opt fringe tabulated-list newcomment lisp-mode prog-mode register
page menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock
font-lock syntax facemenu font-core frame cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese hebrew
greek romanian slovak czech european ethiopic indian cyrillic chinese
case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer nadvice
loaddefs button faces cus-face macroexp files text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process w32notify w32
multi-tty emacs)

Memory information:
((conses 8 82235 6215)
(symbols 32 18449 0)
(miscs 32 37 107)
(strings 16 13853 3976)
(string-bytes 1 388853)
(vectors 8 10917)
(vector-slots 4 395071 4878)
(floats 8 59 257)
(intervals 28 216 41)
(buffers 508 13))

Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
  python-indent-context()
  python-indent--calculate-indentation()
  python-indent-calculate-indentation(nil)
  python-indent-line(nil)
  python-indent-line-function()
  indent-for-tab-command(nil)
  call-interactively(indent-for-tab-command nil nil)
  command-execute(indent-for-tab-command)