[Mac] MacPorts: no destroot found @ Mac OSX 10.11.6

前陣子一直在測試相容性問題，不斷地用 sudo port -fp uninstall installed 清光軟體。但一直懶沒把所有相依性刪光，在安裝 py-pip27 時，就會蹦出以下錯誤訊息：

$ sudo port install py27-pip
--->  Computing dependencies for py27-pip
--->  Installing py27-pip @8.1.2_0
Error: org.macports.install for port py27-pip returned: no destroot found at: /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_python_py-pip/py27-pip/work/destroot
Please see the log file for port py27-pip for details:
    /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_python_py-pip/py27-pip/main.log
To report a bug, follow the instructions in the guide:
    http://guide.macports.org/#project.tickets
Error: Processing of port py27-pip failed

解法就是老老實實參考 MacPorts - 2.4. Uninstall 官方文件清資料，仔細做了以下動作：

$ sudo rm -rf /opt/local/ ~/.macports

下載並安裝最新版 MacPorts: https://distfiles.macports.org/MacPorts/MacPorts-2.3.4-10.11-ElCapitan.pkg

重新安裝需要的軟體：

$ sudo port selfupdate
$ sudo port install py27-pip