Branch merge

diff --cc Misc/NEWS
index dd7dedebf72a714a4dfbbba9473b982f16e33722,e94b77ccdbd3b8f0427ee46e18790a4b87672154..f2d3ffe28cf076015e3c711ca4d8a8cbdbaad8f3
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -187,16 -187,10 +187,20 @@@ Core and Builtin
  Library
  -------
  
+ - Issue #12246: Warn and fail when trying to install a third-party project from
+   an uninstalled Python (built in a source checkout).  Original patch by
+   Tshepang Lekhonkhobe.
+ 
 +- Issue #10694: zipfile now ignores garbage at the end of a zipfile.
 +
 +- Issue #12283: Fixed regression in smtplib quoting of leading dots in DATA.
 +
 +- Issue #10424: Argparse now includes the names of the missing required
 +  arguments in the missing arguments error message.
 +
 +- Issue #12168: SysLogHandler now allows NUL termination to be controlled using
 +  a new 'append_nul' attribute on the handler.
 +
  - Issue #11583: Speed up os.path.isdir on Windows by using GetFileAttributes
    instead of os.stat.