check for valid git version number in pkg

README.md

@@ -253,7 +253,7 @@ Building Julia requires that the following software be installed:
 - **[GNU make]**                — building dependencies.
 - **[gcc & g++][gcc]** (>= 4.4) or **[Clang][clang]** (>= 3.1, Xcode 4.3.3 on OS X) — compiling and linking C, C++
 - **[gfortran][gcc]**           — compiling and linking fortran libraries
-- **[git]**                     — version control and package management.
+- **[git]**                     — version control and package management (version 1.7.3+ required)
 - **[perl]**                    — preprocessing of header files of libraries.
 - **[wget]**, **[curl]**, or **[fetch]** (FreeBSD) — to automatically download external libraries.
 - **[m4]**                      — needed to build GMP.

base/pkg/dir.jl

@@ -30,6 +30,9 @@ end
 
 function init(meta::AbstractString=DEFAULT_META, branch::AbstractString=META_BRANCH)
     dir = path()
+    if Git.version() < v"1.7.3"
+        warn("Pkg only works with git versions greater than v1.7.3")
+    end
     info("Initializing package repository $dir")
     if isdir(joinpath(dir,"METADATA"))
         info("Package directory $dir is already initialized.")

base/pkg/git.jl

@@ -30,6 +30,8 @@ function success(args::Cmd; dir="")
     Base.success(`$g $args`)
 end
 
+version() = VersionNumber(split(Git.readchomp(`version`), ' ')[3])
+
 modules(args::Cmd; dir="") = readchomp(`config -f .gitmodules $args`, dir=dir)
 different(verA::AbstractString, verB::AbstractString, path::AbstractString; dir="") =
     !success(`diff-tree --quiet $verA $verB -- $path`, dir=dir)

test/git.jl

@@ -1,6 +1,8 @@
 import Base.Git
 include("gitutils.jl")
 
+@test Git.version() >= v"1.7.3"
+
 dir = string("tmp.",randstring())
 @test !ispath(dir)
 mkdir(dir)