project: fix encoding handling with git commands

The GitCommand Wait helper takes care of decoding bytes to strings
for us.  That means we don't have to decode stdout ourselves which
is what our local rev list, ls-remote, and generic get_attr helpers
were doing.

If we don't use Wait though to capture the output but instead go
directly to the subprocess stdout, we do have to handle decoding
ourselves.  This is what the diff helpers were doing.

Bug: https://crbug.com/gerrit/10418
Change-Id: I057ca245af3ff18d6b4a074e3900887f06a5617d
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/233076
Reviewed-by: David Pursehouse <dpursehouse@collab.net>
Tested-by: Mike Frysinger <vapier@google.com>

project.py

@@ -1141,6 +1141,8 @@ class Project(object):
                    capture_stderr=True)
     has_diff = False
     for line in p.process.stdout:
+      if not hasattr(line, 'encode'):
+        line = line.decode()
       if not has_diff:
         out.nl()
         out.project('project %s/' % self.relpath)
@@ -1595,7 +1597,7 @@ class Project(object):
     last_mine = None
     cnt_mine = 0
     for commit in local_changes:
-      commit_id, committer_email = commit.decode('utf-8').split(' ', 1)
+      commit_id, committer_email = commit.split(' ', 1)
       if committer_email == self.UserEmail:
         last_mine = commit_id
         cnt_mine += 1
@@ -2406,10 +2408,7 @@ class Project(object):
     cmd = ['ls-remote', self.remote.name, refs]
     p = GitCommand(self, cmd, capture_stdout=True)
     if p.Wait() == 0:
-      if hasattr(p.stdout, 'decode'):
-        return p.stdout.decode('utf-8')
-      else:
-        return p.stdout
+      return p.stdout
     return None
 
   def _Revert(self, rev):
@@ -2820,6 +2819,8 @@ class Project(object):
                      capture_stderr=True)
       try:
         out = p.process.stdout.read()
+        if not hasattr(out, 'encode'):
+          out = out.decode()
         r = {}
         if out:
           out = iter(out[:-1].split('\0'))
@@ -2979,10 +2980,6 @@ class Project(object):
           raise GitError('%s %s: %s' %
                          (self._project.name, name, p.stderr))
         r = p.stdout
-        try:
-          r = r.decode('utf-8')
-        except AttributeError:
-          pass
         if r.endswith('\n') and r.index('\n') == len(r) - 1:
           return r[:-1]
         return r