Most-wanted bug fixes for 2.7

[Matt Mackall]

1. Bug 3984 - Merge with ambiguous ancestor does the wrong thing
http://bz.selenic.com/show_bug.cgi?id=3984

2. Bug 3934 - "hg log -f" fails when largefiles enabled
http://bz.selenic.com/show_bug.cgi?id=3934

3. Bug 3905 - Push hangs on big chunk (Windows 2008R2 + IIS)
http://bz.selenic.com/show_bug.cgi?id=3905

4. Bug 3623 - convert/cvsps doesn't work with Python 2.7.3 on Windows
http://bz.selenic.com/show_bug.cgi?id=3623


-- 
Mathematics is the supreme nostalgia of our time.