title: How to set child process' environment variable in Makefile
body: <p>I would like to change this Makefile:</p>
  
  <pre><code>SHELL := /bin/bash
  PATH  := node_modules/.bin:$(PATH)
  
  boot:
      @supervisor         \
        --harmony         \
        --watch etc,lib       \
        --extensions js,json      \
        --no-restart-on error     \
          lib
  
  test:
      NODE_ENV=test mocha         \
        --harmony             \
        --reporter spec       \
          test
  
  clean:
      @rm -rf node_modules
  
  .PHONY: test clean
  </code></pre>
  
  <p>to:</p>
  
  <pre><code>SHELL := /bin/bash
  PATH  := node_modules/.bin:$(PATH)
  
  boot:
      @supervisor         \
        --harmony         \
        --watch etc,lib       \
        --extensions js,json      \
        --no-restart-on error     \
          lib
  
  test: NODE_ENV=test
  test:
      mocha                   \
        --harmony             \
        --reporter spec       \
          test
  
  clean:
      @rm -rf node_modules
  
  .PHONY: test clean
  </code></pre>
  
  <p>Unfortunately the second one does not work (the node process still runs with the default <code>NODE_ENV</code>.</p>
  
  <p>What did I miss?</p>