$PATH error when installing

[jaxxstorm]

I'm trying to install spread and getting the following error

brew install spread                                                                                                                                                          
==> Installing spread from redspread/spread
==> Downloading https://github.com/redspread/spread/archive/v1.0.0.tar.gz
Already downloaded: /Users/Lee/Library/Caches/Homebrew/spread-1.0.0.tar.gz
==> mkdir -p src/rsprd.com/spread
==> cp -r pkg src/rsprd.com/spread/
==> cp -r cmd src/rsprd.com/spread/
==> cp -r cli src/rsprd.com/spread/
==> cp -r vendor/ src
==> go build -ldflags -X main.Version=v1.0.0 rsprd.com/spread/cmd/spread
Last 15 lines from /Users/Lee/Library/Logs/Homebrew/spread/06.go:
2016-08-21 13:03:57 +0100

go
build
-ldflags
-X main.Version=v1.0.0
rsprd.com/spread/cmd/spread

# pkg-config --cflags libgit2
pkg-config: exec: "pkg-config": executable file not found in $PATH

READ THIS: https://git.io/brew-troubleshooting
If reporting this issue please do so at (not Homebrew/brew):
  https://github.com/redspread/homebrew-spread/issues

These open issues may also help:
Should defer to spread repo for build process https://github.com/redspread/homebrew-spread/issues/1

pkg-config is definitely installed and is in my $PATH:

echo $PATH | cut -d: -f 7                                                                                                                                                      
/usr/local/bin

which pkg-config                                                                                                                                                              
/usr/local/bin/pkg-config

Any ideas what's going on here?