serve-branches: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/serve-branches - from package: loggerhead

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/serve-branches - from package: loggerhead

You may install the required package with command apt-get install {package}

Error in other languages:
serve-branches: bevel nie gevind nie
serve-branches: comandă negăsită
serve-branches: comando não encontrado
serve-branches: commande introuvable
serve-branches: command not found
serve-branches: käsku ei ole
serve-branches: không tìm thấy lệnh
serve-branches: komanda nerasta
serve-branches: Kommando nicht gefunden.
serve-branches: kommandot finns inte
serve-branches: komut yok
serve-branches: nie znaleziono polecenia
serve-branches: níor aimsíodh an t-ordú
serve-branches: no se encontró la orden
serve-branches: no s'ha trobat l'ordre
serve-branches: opdracht niet gevonden
serve-branches: parancs nem található
serve-branches: perintah tidak ditemukan
serve-branches: príkaz nenájdený
serve-branches: příkaz nenalezen
serve-branches: команда не найдена
serve-branches: командата не е открита
serve-branches: 命令找不到
serve-branches: コマンドが見つかりません