RFC patch, 4 partsgit-p4: python 3 compatability

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:

diff --git a/git-p4.py b/git-p4.py
index 60c73b6a37..ead9d816e1 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -36,6 +36,7 @@
     unicode = str
     bytes = bytes
     basestring = (str,bytes)
+    use_encoded_streams = True
 else:
     # 'unicode' exists, must be Python 2
     str = str
@@ -643,6 +644,15 @@ def p4CmdList(cmd, stdin=None, stdin_mode='w+b', cb=None, skip_info=False,
     try:
         while True:
             entry = marshal.load(p4.stdout)
+            if use_encoded_streams:
+                # Decode unmarshalled dict to use str keys and values, except for:
+                #   - `data` which may contain arbitrary binary data
+                #   - `depotFile` which may contain non-UTF8 encoded text
+                decoded_entry = {}
+                for key, value in entry.items():
+                    key = key.decode()
+                    decoded_entry[key] = value.decode() if not (key in ['data', 'depotFile'] or isinstance(value, str)) else value
+                entry = decoded_entry
             if skip_info:
                 if 'code' in entry and entry['code'] == 'info':
                     continue

diff --git a/git-p4.py b/git-p4.py
index d79cbf7005..6821d6aafd 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -1387,14 +1387,14 @@ def getUserMapFromPerforceServer(self):
         for (key, val) in self.users.items():
             s += "%s\t%s\n" % (key.expandtabs(1), val.expandtabs(1))
 
-        open(self.getUserCacheFilename(), "wb").write(s)
+        open(self.getUserCacheFilename(), 'w', encoding='utf-8').write(s)
         self.userMapFromPerforceServer = True
 
     def loadUserMapFromCache(self):
         self.users = {}
         self.userMapFromPerforceServer = False
         try:
-            cache = open(self.getUserCacheFilename(), "rb")
+            cache = open(self.getUserCacheFilename(), 'r', encoding='utf-8')
             lines = cache.readlines()
             cache.close()
             for line in lines:

diff --git a/git-p4.py b/git-p4.py
index 6821d6aafd..bd693e1404 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -650,11 +650,27 @@ def p4CmdList(cmd, stdin=None, stdin_mode='w+b', cb=None, skip_info=False,
             if use_encoded_streams:
                 # Decode unmarshalled dict to use str keys and values, except for:
                 #   - `data` which may contain arbitrary binary data
-                #   - `depotFile` which may contain non-UTF8 encoded text
+                #   - `depotFile` which may contain non-UTF8 encoded text, and is decoded
+                #     according to git-p4.pathEncoding config
                 decoded_entry = {}
                 for key, value in entry.items():
                     key = key.decode()
-                    decoded_entry[key] = value.decode() if not (key in ['data', 'depotFile'] or isinstance(value, str)) else value
+                    if key == 'data':
+                        pass
+                    elif key == 'depotFile':
+                        try:
+                            value = value.decode('ascii')
+                        except:
+                            encoding = 'utf-8'
+                            if gitConfig('git-p4.pathEncoding'):
+                                encoding = gitConfig('git-p4.pathEncoding')
+                            path = path.decode(encoding, 'replace')
+                            if verbose:
+                                print('Path with non-ASCII characters detected. Used %s to decode: %s ' % (encoding, path))
+                    elif not isinstance(value, str):
+                        value = value.decode()
+
+                    decoded_entry[key] = value
                 entry = decoded_entry
             if skip_info:
                 if 'code' in entry and entry['code'] == 'info':
@@ -2758,24 +2774,11 @@ def writeToGitStream(self, gitMode, relPath, contents):
             self.gitStream.write(d)
         self.gitStream.write('\n')
 
-    def encodeWithUTF8(self, path):
-        try:
-            path.decode('ascii')
-        except:
-            encoding = 'utf8'
-            if gitConfig('git-p4.pathEncoding'):
-                encoding = gitConfig('git-p4.pathEncoding')
-            path = path.decode(encoding, 'replace').encode('utf8', 'replace')
-            if self.verbose:
-                print('Path with non-ASCII characters detected. Used %s to encode: %s ' % (encoding, path))
-        return path
-
     # output one file from the P4 stream
     # - helper for streamP4Files
 
     def streamOneP4File(self, file, contents):
         relPath = self.stripRepoPath(file['depotFile'], self.branchPrefixes)
-        relPath = self.encodeWithUTF8(relPath)
         if verbose:
             if 'fileSize' in self.stream_file:
                 size = int(self.stream_file['fileSize'])
@@ -2858,7 +2861,6 @@ def streamOneP4File(self, file, contents):
 
     def streamOneP4Deletion(self, file):
         relPath = self.stripRepoPath(file['path'], self.branchPrefixes)
-        relPath = self.encodeWithUTF8(relPath)
         if verbose:
             sys.stdout.write("delete %s\n" % relPath)
             sys.stdout.flush()