diff --git a/Library/Homebrew/brew.sh b/Library/Homebrew/brew.sh
index bd88a23f51..c8f66bd459 100644
--- a/Library/Homebrew/brew.sh
+++ b/Library/Homebrew/brew.sh
@@ -246,16 +246,6 @@ case "$HOMEBREW_COMMAND" in
   --config)    HOMEBREW_COMMAND="config" ;;
 esac
 
-if [[ -z "$HOMEBREW_DEVELOPER" ]]
-then
-  export HOMEBREW_GIT_CONFIG_FILE="$HOMEBREW_REPOSITORY/.git/config"
-  HOMEBREW_GIT_CONFIG_DEVELOPERMODE="$(git config --file="$HOMEBREW_GIT_CONFIG_FILE" --get homebrew.devcmdrun 2>/dev/null)"
-  if [[ "$HOMEBREW_GIT_CONFIG_DEVELOPERMODE" = "true" ]]
-  then
-    export HOMEBREW_DEV_CMD_RUN="1"
-  fi
-fi
-
 if [[ -f "$HOMEBREW_LIBRARY/Homebrew/cmd/$HOMEBREW_COMMAND.sh" ]]
 then
   HOMEBREW_BASH_COMMAND="$HOMEBREW_LIBRARY/Homebrew/cmd/$HOMEBREW_COMMAND.sh"
diff --git a/Library/Homebrew/system_config.rb b/Library/Homebrew/system_config.rb
index ef7572d227..28eecf951f 100644
--- a/Library/Homebrew/system_config.rb
+++ b/Library/Homebrew/system_config.rb
@@ -185,6 +185,7 @@ class SystemConfig
         HOMEBREW_BREW_FILE
         HOMEBREW_COMMAND_DEPTH
         HOMEBREW_CURL
+        HOMEBREW_GIT_CONFIG_FILE
         HOMEBREW_LIBRARY
         HOMEBREW_MACOS_VERSION
         HOMEBREW_RUBY_PATH
diff --git a/bin/brew b/bin/brew
index 390fcc1d66..4ac9473a77 100755
--- a/bin/brew
+++ b/bin/brew
@@ -59,6 +59,29 @@ do
   export "$VAR_NEW"="${!VAR}"
 done
 
+# Set HOMEBREW_DEVELOPER for users who have run a development command
+if [[ -z "$HOMEBREW_DEVELOPER" ]]
+then
+  export HOMEBREW_GIT_CONFIG_FILE="$HOMEBREW_REPOSITORY/.git/config"
+  HOMEBREW_GIT_CONFIG_DEVELOPERMODE="$(git config --file="$HOMEBREW_GIT_CONFIG_FILE" --get homebrew.devcmdrun 2>/dev/null)"
+  if [[ "$HOMEBREW_GIT_CONFIG_DEVELOPERMODE" = "true" ]]
+  then
+    export HOMEBREW_DEV_CMD_RUN="1"
+  fi
+fi
+
+if [[ -z "$HOMEBREW_NO_ENV_FILTERING" ]]
+then
+  if [[ -n "$HOMEBREW_DEVELOPER" || -n "$HOMEBREW_DEV_CMD_RUN" ]]
+  then
+    # Use env filtering by default for users who have run a development command
+    # This will be enabled by default for all users in future.
+    export HOMEBREW_ENV_FILTERING="1"
+  fi
+else
+  unset HOMEBREW_ENV_FILTERING
+fi
+
 # test-bot sets environment filtering itself
 if [[ -n "$HOMEBREW_ENV_FILTERING" && "$1" != "test-bot" ]]
 then