[RFC PATCH 2/4] git-p4: properly encode/decode communication with git for python 3

[Yang Zhao <yang.zhao@skyboxlabs.com>]

Under python3, calls to write() on the stream to `git fast-import` must
be encoded.  This patch wraps the IO object such that this encoding is
done transparently.

Conversely, any text data read from subprocesses must also be decoded
before running through the rest of the pipeline.

Signed-off-by: Yang Zhao <yang.zhao@skyboxlabs.com>
---
 git-p4.py | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/git-p4.py b/git-p4.py
index ead9d816e1..d79cbf7005 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -237,6 +237,9 @@ def read_pipe_lines(c):
     if pipe.close() or p.wait():
         die('Command failed: %s' % str(c))
 
+    if use_encoded_streams:
+        val = [line.decode() for line in val]
+
     return val
 
 def p4_read_pipe_lines(c):
@@ -631,7 +634,7 @@ def p4CmdList(cmd, stdin=None, stdin_mode='w+b', cb=None, skip_info=False,
             stdin_file.write(stdin)
         else:
             for i in stdin:
-                stdin_file.write(i + '\n')
+                stdin_file.write((i + '\n').encode())
         stdin_file.flush()
         stdin_file.seek(0)
 
@@ -3547,6 +3550,15 @@ def openStreams(self):
         self.gitStream = self.importProcess.stdin
         self.gitError = self.importProcess.stderr
 
+        if use_encoded_streams:
+            # Wrap gitStream.write() so that it can be called using `str` arguments
+            def make_encoded_write(write):
+                def encoded_write(s):
+                    return write(s.encode() if isinstance(s, str) else s)
+                return encoded_write
+
+            self.gitStream.write = make_encoded_write(self.gitStream.write)
+
     def closeStreams(self):
         self.gitStream.close()
         if self.importProcess.wait() != 0:
-- 
2.24.0.windows.2