I had tried to raise a bug in bugtracker but it was declined by project manager
saying there is no error in package updater.Yes there is no error in it .The error is with installation method .
The installation tool you used to install ispconfig is not compatible with ispconfig 3.0.5 if it does not install php5-curl, it is not developed nor supported by the ispconfig project. So you will understand that we wil not accpet bugreports caused by third party software, especially when several core devs confirmed that the bug does not exist when the system is installed as described in the official guides.
If you want to get a correct and complete install of ispconfig, use one of the official installation guides from ispconfig.org