diff --git a/Library/Homebrew/brew.sh b/Library/Homebrew/brew.sh
index c8f66bd459..ff9176099e 100644
--- a/Library/Homebrew/brew.sh
+++ b/Library/Homebrew/brew.sh
@@ -246,6 +246,18 @@ case "$HOMEBREW_COMMAND" in
   --config)    HOMEBREW_COMMAND="config" ;;
 esac
 
+# Set HOMEBREW_DEV_CMD_RUN for users who have run a development command.
+# This makes them behave like HOMEBREW_DEVELOPERs for brew update.
+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/$HOMEBREW_COMMAND.sh"
diff --git a/bin/brew b/bin/brew
index e70c01fd73..7270aec83b 100755
--- a/bin/brew
+++ b/bin/brew
@@ -59,35 +59,13 @@ do
   export "$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" && "$1" != "test-bot" ]]
+# test-bot does environment filtering itself
+if [[ -z "$HOMEBREW_NO_ENV_FILTERING" && "$1" != "test-bot" ]]
 then
   PATH="/usr/bin:/bin:/usr/sbin:/sbin"
 
   FILTERED_ENV=()
+  # Filter all but the specific variables.
   for VAR in HOME SHELL PATH TERM LOGNAME USER CI TRAVIS SSH_AUTH_SOCK SUDO_ASKPASS \
              http_proxy https_proxy ftp_proxy HTTPS_PROXY FTP_PROXY \
              "${!HOMEBREW_@}" "${!TRAVIS_@}" "${!JENKINS_@}"