From aa67d8f6f192437439db48039f0d1c110e7ea7ca Mon Sep 17 00:00:00 2001
From: Stefan Karpinski <stefan@karpinski.org>
Date: Sat, 14 Sep 2013 15:13:04 -0400
Subject: [PATCH] Pkg.tag: read requires from the given commit, not head.

---
 base/pkg.jl      | 15 +++++++++++----
 base/pkg/reqs.jl |  4 ++--
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/base/pkg.jl b/base/pkg.jl
index b3ad725eb4a43..d3e0f13a26625 100644
--- a/base/pkg.jl
+++ b/base/pkg.jl
@@ -338,14 +338,21 @@ tag(pkg::String, ver::Union(Symbol,VersionNumber)=:bump;
     registered || return
     try
         info("Writing METADATA for $pkg v$ver")
-        reqs = Reqs.parse(joinpath(pkg,"REQUIRE"))
+        reqs = Reqs.parse(Git.cmd(`cat-file blob $commit:REQUIRE`,dir=pkg))
         cd("METADATA") do
             Git.transact() do
                 d = joinpath(pkg,"versions",string(ver))
                 mkpath(d)
-                open(io->println(io,commit), joinpath(d,"sha1"), "w")
-                isempty(reqs) || Reqs.write(joinpath(d,"requires"), reqs)
-                Git.run(`add $d`)
+                sha1file = joinpath(d,"sha1")
+                open(io->println(io,commit), sha1file, "w")
+                Git.run(`add $sha1file`)
+                reqsfile = joinpath(d,"requires")
+                if isempty(reqs)
+                    ispath(reqsfile) && Git.run(`rm -f -q $reqsfile`)
+                else
+                    Reqs.write(reqsfile,reqs)
+                    Git.run(`add $reqsfile`)
+                end
             end
         end
     catch
diff --git a/base/pkg/reqs.jl b/base/pkg/reqs.jl
index b3b7f020ddd68..9c07e11a44784 100644
--- a/base/pkg/reqs.jl
+++ b/base/pkg/reqs.jl
@@ -37,9 +37,9 @@ end
 
 # general machinery for parsing REQUIRE files
 
-function read(io::IO)
+function read(readable::Union(IO,Base.AbstractCmd))
     lines = Line[]
-    for line in eachline(io)
+    for line in eachline(readable)
         line = chomp(line)
         push!(lines, ismatch(r"^\s*(?:#|$)", line) ? Comment(line) : Requirement(line))
     end