diff --git a/tool/vcs.rb b/tool/vcs.rb
index 618a788dc7..86e7e50f0c 100644
--- a/tool/vcs.rb
+++ b/tool/vcs.rb
@@ -399,7 +399,7 @@ class VCS
     end
 
     def self.cmd_read_at(srcdir, cmds)
-      IO.pread(*cmd_args(cmds, srcdir))
+      without_gitconfig { IO.pread(*cmd_args(cmds, srcdir)) }
     end
 
     def self.get_revisions(path, srcdir = nil)
@@ -444,6 +444,13 @@ class VCS
       rev[0, 10]
     end
 
+    def self.without_gitconfig
+      home = ENV.delete('HOME')
+      yield
+    ensure
+      ENV['HOME'] = home if home
+    end
+
     def initialize(*)
       super
       if srcdir = @srcdir and self.class.local_path?(srcdir)