Add missing dependencies for Flake8 (#1883)

* Warn user if flake8 can't find setuptools

* Add missing dependencies of flake8

* Updates to py-autopep8, make packages activateable

* Check for presence of setuptools for Sphinx too

* Fix bug in order of commands

share/spack/qa/run-flake8-tests

@@ -23,10 +23,6 @@ deps=(
 # Check for dependencies
 "$QA_DIR/check_dependencies" "${deps[@]}" || exit 1
 
-# Move to root directory of Spack
-# Allows script to be run from anywhere
-cd "$SPACK_ROOT"
-
 # Gather array of changed files
 changed=($("$QA_DIR/changed_files" "*.py"))
 
@@ -36,6 +32,10 @@ if [[ ! "${changed[@]}" ]]; then
     exit 0
 fi
 
+# Move to root directory of Spack
+# Allows script to be run from anywhere
+cd "$SPACK_ROOT"
+
 function cleanup {
     # Restore original package files after modifying them.
     for file in "${changed[@]}"; do