[PATCH 03 of 11] ui: use latin-1 as "fat bytes" to preserve EOL behavior on py3

[Augie Fackler]

# HG changeset patch
# User Augie Fackler <raf at durin42.com>
# Date 1490562355 14400
#      Sun Mar 26 17:05:55 2017 -0400
# Node ID 25355685cfaced26214c1fb89d191c3705dc52c7
# Parent  28149aad82cb12522f1ba50b0bb184d1f960a9c9
ui: use latin-1 as "fat bytes" to preserve EOL behavior on py3

This avoids the encoding issues present in the last patch which would
have led to problems in the future. Thanks to Yuya for the idea.

diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -1212,8 +1212,16 @@ class ui(object):
                                       suffix=extra['suffix'], text=True,
                                       dir=rdir)
         try:
-            f = os.fdopen(fd, pycompat.sysstr("w"))
-            f.write(encoding.strfromlocal(text))
+            if pycompat.ispy3:
+                # We use latin-1 as "fat bytes" so that we still get
+                # free EOL conversion on Python 3, but we avoid
+                # encode/decode problems.
+                f = os.fdopen(fd, pycompat.sysstr("w"),
+                              encoding=pycompat.sysstr("latin-1"))
+                f.write(text.decode("latin-1"))
+            else:
+                f = os.fdopen(fd, pycompat.sysstr("w"))
+                f.write(text)
             f.close()
 
             environ = {'HGUSER': user}
@@ -1235,8 +1243,14 @@ class ui(object):
                         onerr=error.Abort, errprefix=_("edit failed"),
                         blockedtag='editor')
 
-            f = open(name)
-            t = encoding.strtolocal(f.read())
+            if pycompat.ispy3:
+                # See above about "fat bytes" and latin-1.
+                f = open(name, pycompat.sysstr("r"),
+                         encoding=pycompat.sysstr("latin-1"))
+                t = f.read().encode("latin-1")
+            else:
+                f = open(name, pycompat.sysstr("r"))
+                t = f.read()
             f.close()
         finally:
             os.unlink(name)