phabricator error

gistfile1.txt

PHABRICATOR SETUP

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                This setup mode will guide you through setting up your Phabricator configuration.


>>>  CORE CONFIGURATION  -------------------------------------------------------

 okay  PHP's deprecated 'safe_mode' is disabled.
 okay  'open_basedir' is not set.
[WARN] You have not configured 'security.alternate-file-domain'. This makes your installation vulnerable to attack. Make sure you read the documentation for this parameter and understand the consequences of leaving it unconfigured.
 okay  $PATH is nonempty.
[OKAY] Core configuration OKAY.


>>>  REQUIRED PHP EXTENSIONS  --------------------------------------------------

 okay  Extension 'mysql' installed.
 okay  Extension 'hash' installed.
 okay  Extension 'json' installed.
 okay  Extension 'openssl' installed.
 okay  Extension 'mbstring' installed.
 okay  Extension 'iconv' installed.
 okay  Extension 'curl' installed.
 okay  PHP binary found on the command line.
 okay  PHP is available from the command line.
 okay  'php' is CLI SAPI.
 okay  pcntl is available from the command line.
[OKAY] All extensions OKAY


>>>  GIT SUBMODULES  -----------------------------------------------------------

EXCEPTION!
exception 'CommandException' with message 'Command failed with error #1!
COMMAND
(cd '/opt/app/phabricator' && git submodule status)

STDOUT
(empty)

STDERR
/usr/lib/git-core/git-submodule: 7: /usr/lib/git-core/git-submodule: sed: not found
/usr/lib/git-core/git-submodule: 74: /usr/lib/git-core/git-sh-setup: sed: not found
basename: write error: Broken pipe
/usr/lib/git-core/git-submodule: 238: /usr/lib/git-core/git-sh-setup: uname: not found
/usr/lib/git-core/git-submodule: 104: /usr/lib/git-core/git-submodule: sed: not found
/usr/lib/git-core/git-submodule: 106: /usr/lib/git-core/git-submodule: sed: not found
No submodule mapping found in .gitmodules for path 'externals/javelin'
' in /opt/app/libphutil/src/future/exec/ExecFuture.php:318
Stack trace:
#0 /opt/app/libphutil/src/future/exec/execx.php(18): ExecFuture->resolvex()
#1 /opt/app/phabricator/src/infrastructure/PhabricatorSetup.php(248): execx('(cd %s && git s...', '/opt/app/phabri...')
#2 /opt/app/phabricator/webroot/index.php(33): PhabricatorSetup::runSetup()
#3 {main}