Add tags file to gitignore.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Use ||= instead of .nil?.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
mail: prefer single-quoted strings.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Don't instantiate the object passed to fail.

Let the function do that for us.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Use File.join where appropriate.

extruder is not likely to work especially well on non-Unix systems, but
the documentary value is beneficial by itself.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Avoid needless if block.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
spec: prefer single-quoted strings.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>