use print() instead of sys.stdout.write()

We're relying on sys.stdout.write() to flush its buffer which isn't
guaranteed, and is not the case in Python 3.  Change to use print()
everywhere to be standard, and utilize the end= keyword to get the
EOL semantics we need.

We can't use print's flush= keyword as that's only in Python 3.
Leave behind a TODO to clean it up when we can drop Python 2.

Bug: https://crbug.com/gerrit/10418
Change-Id: I562128c7f1e6d154f4a6ecdf33a70fa2811dc2af
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/230392
Tested-by: Mike Frysinger <vapier@google.com>
Reviewed-by: David Pursehouse <dpursehouse@collab.net>

subcmds/init.py

@@ -294,7 +294,9 @@ to update the working directory files.
       sys.exit(1)
 
   def _Prompt(self, prompt, value):
-    sys.stdout.write('%-10s [%s]: ' % (prompt, value))
+    print('%-10s [%s]: ' % (prompt, value), end='')
+    # TODO: When we require Python 3, use flush=True w/print above.
+    sys.stdout.flush()
     a = sys.stdin.readline().strip()
     if a == '':
       return value
@@ -328,7 +330,9 @@ to update the working directory files.
 
       print()
       print('Your identity is: %s <%s>' % (name, email))
-      sys.stdout.write('is this correct [y/N]? ')
+      print('is this correct [y/N]? ', end='')
+      # TODO: When we require Python 3, use flush=True w/print above.
+      sys.stdout.flush()
       a = sys.stdin.readline().strip().lower()
       if a in ('yes', 'y', 't', 'true'):
         break
@@ -370,7 +374,9 @@ to update the working directory files.
       out.printer(fg='black', attr=c)(' %-6s ', c)
     out.nl()
 
-    sys.stdout.write('Enable color display in this user account (y/N)? ')
+    print('Enable color display in this user account (y/N)? ', end='')
+    # TODO: When we require Python 3, use flush=True w/print above.
+    sys.stdout.flush()
     a = sys.stdin.readline().strip().lower()
     if a in ('y', 'yes', 't', 'true', 'on'):
       gc.SetString('color.ui', 'auto')

subcmds/upload.py

@@ -221,7 +221,9 @@ Gerrit Code Review:  https://www.gerritcodereview.com/
       for commit in commit_list:
         print('         %s' % commit)
 
-      sys.stdout.write('to %s (y/N)? ' % remote.review)
+      print('to %s (y/N)? ' % remote.review, end='')
+      # TODO: When we require Python 3, use flush=True w/print above.
+      sys.stdout.flush()
       answer = sys.stdin.readline().strip().lower()
       answer = answer in ('y', 'yes', '1', 'true', 't')
 
@@ -360,10 +362,13 @@ Gerrit Code Review:  https://www.gerritcodereview.com/
 
           # if they want to auto upload, let's not ask because it could be automated
           if answer is None:
-            sys.stdout.write('Uncommitted changes in ' + branch.project.name)
-            sys.stdout.write(' (did you forget to amend?):\n')
-            sys.stdout.write('\n'.join(changes) + '\n')
-            sys.stdout.write('Continue uploading? (y/N) ')
+            print()
+            print('Uncommitted changes in %s (did you forget to amend?):'
+                  % branch.project.name)
+            print('\n'.join(changes))
+            print('Continue uploading? (y/N) ', end='')
+            # TODO: When we require Python 3, use flush=True w/print above.
+            sys.stdout.flush()
             a = sys.stdin.readline().strip().lower()
             if a not in ('y', 'yes', 't', 'true', 'on'):
               print("skipping upload", file=sys.stderr)