From cd7049bb72faaae6bebe0739b5ffef0eed5e6648 Mon Sep 17 00:00:00 2001
From: Mike McQuaid <mike@mikemcquaid.com>
Date: Mon, 27 Nov 2017 14:43:24 +0000
Subject: [PATCH] bin/brew: don't set empty, unfiltered variables.

Otherwise we unconditionally set e.g. `CI`, `TRAVIS`.
---
 bin/brew | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/bin/brew b/bin/brew
index 4ac9473a77..7d36ff92d5 100755
--- a/bin/brew
+++ b/bin/brew
@@ -91,6 +91,9 @@ then
   for VAR in HOME SHELL PATH TERM LOGNAME USER CI TRAVIS \
              "${!HOMEBREW_@}" "${!TRAVIS_@}"
   do
+    # Skip if variable value is empty.
+    [[ -z "${!VAR}" ]] && continue
+
     FILTERED_ENV+=( "${VAR}=${!VAR}" )
   done