我正在尝试在沙箱中安装一个项目，我有不同的分支。 当我结帐一个分支并进行cabal安装时，它就像一阵微风。 但是，当我结帐另一个分支时，我得到：
cabal: No cabal file found.
Please create a package description file <pkgname>.cabal
但是有一个cabal文件！我不明白。
编辑：做完cabal安装后-v3
Using a sandbox located at
~/projets/alternative/m_p/MP/.cabal-sandbox
Searching for ghc in path.
Found ghc at /usr/bin/ghc
("/usr/bin/ghc",["--numeric-version"])
/usr/bin/ghc is version 7.4.1
looking for tool ghc-pkg near compiler in /usr/bin
found ghc-pkg in /usr/bin/ghc-pkg
("/usr/bin/ghc-pkg",["--version"])
/usr/bin/ghc-pkg is version 7.4.1
("/usr/bin/ghc",["--supported-languages"])
("/usr/bin/ghc",["--info"])
The package database already exists:
~/projets/alternative/m_p/MP/.cabal-sandbox/i386-linux-ghc-7.4.1-packages.conf.d
Reading available packages...
cabal: No cabal file found.
Please create a package description file <pkgname>.cabal