[file] fix glob_paths when NO paths match, add tests.

README.recipes.md

 <!--- AUTOGENERATED BY `./recipes.py test train` -->
 # Package documentation for [recipe\_engine](https://github.com/luci/recipes-py)
 ## Table of Contents
 
 **[Recipe Modules](#recipe-modules)**
   * [context](#recipe_modules--context) &mdash; The context module provides APIs for manipulating a few pieces of 'ambient' data that affect how steps are run:   cwd - The current working directory.
   * [file](#recipe_modules--file)
   * [generator_script](#recipe_modules--generator_script)
   * [json](#recipe_modules--json) &mdash; Methods for producing and consuming JSON.
   * [path](#recipe_modules--path)
@@ skipping 30 matching lines @@
   * [engine_tests/nonexistent_command](#recipes--engine_testsnonexistent_command)
   * [engine_tests/recipe_paths](#recipes--engine_testsrecipe_paths) &mdash; Tests that recipes have access to names, resources and their package.
   * [engine_tests/sort_properties](#recipes--engine_testssort_properties) &mdash; Tests that step presentation properties can be ordered.
   * [engine_tests/step_stack_exhaustion](#recipes--engine_testsstep_stack_exhaustion) &mdash; Tests that placeholders can't wreck the world by exhausting the step stack.
   * [engine_tests/undeclared_method](#recipes--engine_testsundeclared_method)
   * [engine_tests/unicode](#recipes--engine_testsunicode)
   * [engine_tests/whitelist_steps](#recipes--engine_testswhitelist_steps) &mdash; Tests that step_data can accept multiple specs at once.
   * [file:examples/copy](#recipes--fileexamplescopy)
   * [file:examples/copytree](#recipes--fileexamplescopytree)
   * [file:examples/error](#recipes--fileexampleserror)
+  * [file:examples/glob](#recipes--fileexamplesglob)
   * [generator_script:examples/full](#recipes--generator_scriptexamplesfull)
   * [json:examples/full](#recipes--jsonexamplesfull)
   * [path:examples/full](#recipes--pathexamplesfull)
   * [platform:examples/full](#recipes--platformexamplesfull)
   * [properties:examples/full](#recipes--propertiesexamplesfull)
   * [python:examples/full](#recipes--pythonexamplesfull) &mdash; Launches the repo bundler.
   * [raw_io:examples/full](#recipes--raw_ioexamplesfull)
   * [shutil:examples/full](#recipes--shutilexamplesfull)
   * [step:examples/full](#recipes--stepexamplesfull)
   * [step:tests/active_result](#recipes--steptestsactive_result)
@@ skipping 1094 matching lines @@
 ### *recipes* / [file:examples/copytree](/recipe_modules/file/examples/copytree.py)
 
 [DEPS](/recipe_modules/file/examples/copytree.py#L5): [file](#recipe_modules--file), [path](#recipe_modules--path)
 
 &mdash; **def [RunSteps](/recipe_modules/file/examples/copytree.py#L11)(api):**
 ### *recipes* / [file:examples/error](/recipe_modules/file/examples/error.py)
 
 [DEPS](/recipe_modules/file/examples/error.py#L5): [file](#recipe_modules--file), [path](#recipe_modules--path)
 
 &mdash; **def [RunSteps](/recipe_modules/file/examples/error.py#L11)(api):**
+### *recipes* / [file:examples/glob](/recipe_modules/file/examples/glob.py)
+
+[DEPS](/recipe_modules/file/examples/glob.py#L5): [file](#recipe_modules--file), [json](#recipe_modules--json), [path](#recipe_modules--path)
+
+&mdash; **def [RunSteps](/recipe_modules/file/examples/glob.py#L11)(api):**
 ### *recipes* / [generator\_script:examples/full](/recipe_modules/generator_script/examples/full.py)
 
 [DEPS](/recipe_modules/generator_script/examples/full.py#L7): [generator\_script](#recipe_modules--generator_script), [json](#recipe_modules--json), [path](#recipe_modules--path), [properties](#recipe_modules--properties), [step](#recipe_modules--step)
 
 &mdash; **def [RunSteps](/recipe_modules/generator_script/examples/full.py#L19)(api, script_name):**
 ### *recipes* / [json:examples/full](/recipe_modules/json/examples/full.py)
 
 [DEPS](/recipe_modules/json/examples/full.py#L5): [json](#recipe_modules--json), [path](#recipe_modules--path), [properties](#recipe_modules--properties), [python](#recipe_modules--python), [raw\_io](#recipe_modules--raw_io), [step](#recipe_modules--step)
 
 &mdash; **def [RunSteps](/recipe_modules/json/examples/full.py#L16)(api):**
@@ skipping 98 matching lines @@
 
 [DEPS](/recipe_modules/url/tests/validate_url.py#L5): [properties](#recipe_modules--properties), [step](#recipe_modules--step), [url](#recipe_modules--url)
 
 &mdash; **def [RunSteps](/recipe_modules/url/tests/validate_url.py#L12)(api):**
 ### *recipes* / [uuid:examples/full](/recipe_modules/uuid/examples/full.py)
 
 [DEPS](/recipe_modules/uuid/examples/full.py#L5): [step](#recipe_modules--step), [uuid](#recipe_modules--uuid)
 
 &mdash; **def [RunSteps](/recipe_modules/uuid/examples/full.py#L11)(api):**