A representative from Google Enterprise Support named Jordan gave me the revised appcfg.cmd file below. It helped get me past the error I was having. Unfortunately there's another issue now, but I think the solution below addresses the original error I posted about. Thanks Heeryu and Tatiana for your offers of help.
@echo off
rem Copyright 2013 Google Inc. All Rights Reserved.
cmd /c "python "%~dp0bootstrapping\prerun.py" --command-name=appcfg-java --component-id=gae-java --check-credentials --check-updates"
IF %ERRORLEVEL% NEQ 0 (
EXIT /B %ERRORLEVEL%
)
SETLOCAL
set TMPFILE=%APPDATA%\gcloud\tmp-env-info-%RANDOM%.txt
cmd /c "python "%~dp0bootstrapping\print_env_info.py" gae_java_path > "%TMPFILE%"
IF %ERRORLEVEL% NEQ 0 (
EXIT /B %ERRORLEVEL%
)
set /p credential_path= < "%TMPFILE%"
del "%TMPFILE%"
cmd /c ""%~dp0..\platform/appengine-java-sdk\bin\appcfg.cmd" --oauth2 --oauth2_config_file="%credential_path%" %*"
IF %ERRORLEVEL% NEQ 0 (
EXIT /B %ERRORLEVEL%
)
ENDLOCAL