gbp-clone: command not found

Have You tried accessing the binary with the full path?

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 Debian possible default full paths are:

/usr/bin/gbp-clone - from package: git-buildpackage

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