Can't upgrade curl. It conflicts with kerberos5

[roman.l@…]

$ sudo port upgrade curl

---> Computing dependencies for curl

Error: Unable to upgrade port: Can't install curl because conflicting ports are installed: kerberos5

$ sudo port upgrade git-core

---> Computing dependencies for curl

Error: Unable to upgrade port: Can't install curl because conflicting ports are installed: kerberos5

Please, can anyone tell me how to resolve this conflict? Other ports depends on kerberos5:

$ sudo port uninstall --follow-dependencies kerberos5

---> Unable to uninstall kerberos5 @1.11.3_0, the following ports depend on it:

---> cyrus-sasl2 @2.1.25_4+kerberos

---> cclient @2007f_0

---> php5-imap @5.3.26_0

---> php5-openssl @5.3.26_0

---> php5-imap @5.3.27_0

---> php5-openssl @5.3.27_0

Error: org.macports.uninstall for port kerberos5 returned: Please uninstall the ports that depend on kerberos5 first.

If i try to uninstall for example cyrus-sasl2 i get the following message:

$ sudo port uninstall cyrus-sasl2

---> Unable to uninstall cyrus-sasl2 @2.1.25_4+kerberos, the following ports depend on it:

---> openldap @2.4.31_3

---> subversion @1.7.10_1

---> subversion-perlbindings-5.12 @1.7.10_0

---> subversion @1.8.3_3

---> subversion-perlbindings-5.12 @1.8.3_2

Error: org.macports.uninstall for port cyrus-sasl2 returned: Please uninstall the ports that depend on cyrus-sasl2 first.

It seems to be an endless story ;-)

thanks in advance :-)