dh_ruby_fixdepends: 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 Debian possible default full paths are:

/usr/bin/dh_ruby_fixdepends - from package: gem2deb

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

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