Merge with 3.2 Issue #10639: reindent.py should not convert newlines.

reindent.py now will use the newline detected in the original file and will report an error if mixed newlines are encountered.

diff --cc Misc/NEWS
index c740b2029a9b6bd988d037bcb37bcdbe2f94dec4,d91a9932054ba604f34629047957c4ff90891d71..eb55f291cf3026cc0ad66a5a9ba824bbfa25c6ce
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -1068,11 -749,8 +1068,14 @@@ IDL
  Tools/Demos
  -----------
  
 +- Issue #11996: libpython (gdb), replace "py-bt" command by "py-bt-full" and
 +  add a smarter "py-bt" command printing a classic Python traceback.
 +
  - Issue #11179: Make ccbench work under Python 3.1 and 2.7 again.
  
++- Issue #10639: reindent.py no longer converts newlines and will raise
++  an error if attempting to convert a file with mixed newlines.
++
  Extension Modules
  -----------------
  
@@@ -6661,4 -6210,4 +6664,4 @@@ Doc
  ----
  
  
--**(For information about older versions, consult the HISTORY file.)**
++**(For information about older versions, consult the HISTORY file.)**