yaml: use ruamel.yaml instead of pyyaml

- ruamel.yaml allows round-tripping comments from/to files
- ruamel.yaml is single-source, python2/python3 compatible

bin/spack

@@ -49,13 +49,6 @@ if sys.version_info[:2] == (2, 6):
 
 sys.path.insert(0, spack_external_libs)
 
-# Handle vendoring of YAML specially, as it has two versions.
-if sys.version_info[0] == 2:
-    spack_yaml_libs = os.path.join(spack_external_libs, "yaml/lib")
-else:
-    spack_yaml_libs = os.path.join(spack_external_libs, "yaml/lib3")
-sys.path.insert(0, spack_yaml_libs)
-
 # Once we've set up the system path, run the spack main method
 import spack.main  # noqa
 sys.exit(spack.main.main())

lib/spack/external/__init__.py

@@ -118,12 +118,17 @@
   vendored copy ever needs to be updated again:
   https://github.com/spack/spack/pull/6801/commits/ff513c39f2c67ff615de5cbc581dd69a8ec96526
 
-pyyaml
+ruamel.yaml
 ------
 
-* Homepage: https://pypi.python.org/pypi/PyYAML
-* Usage: Used for config files.
-* Version: 3.12
+* Homepage: https://yaml.readthedocs.io/
+* Usage: Used for config files. Ruamel is based on PyYAML but is more
+  actively maintained and has more features, including round-tripping
+  comments read from config files.
+* Version: 0.11.15 (last version supporting Python 2.6)
+* Note: This package has been slightly modified to improve Python 2.6
+  compatibility -- some ``{}`` format strings were replaced, and the
+  import for ``OrderedDict`` was tweaked.
 
 six
 ---

lib/spack/external/ruamel/yaml/.ruamel/__init__.py

@@ -0,0 +1,2 @@
+import pkg_resources
+pkg_resources.declare_namespace(__name__)

lib/spack/external/ruamel/yaml/LICENSE

@@ -0,0 +1,21 @@
+
+ The MIT License (MIT)
+
+ Permission is hereby granted, free of charge, to any person obtaining a copy
+ of this software and associated documentation files (the "Software"), to deal
+ in the Software without restriction, including without limitation the rights
+ to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ copies of the Software, and to permit persons to whom the Software is
+ furnished to do so, subject to the following conditions:
+
+ The above copyright notice and this permission notice shall be included in
+ all copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 
+ THE SOFTWARE.
+

lib/spack/external/ruamel/yaml/README.rst

@@ -0,0 +1,38 @@
+
+ruamel.yaml
+===========
+
+``ruamel.yaml`` is a YAML 1.2 loader/dumper package for Python.
+
+* `Overview <http://yaml.readthedocs.org/en/latest/overview.html>`_
+* `Installing <http://yaml.readthedocs.org/en/latest/install.html>`_
+* `Details <http://yaml.readthedocs.org/en/latest/detail.html>`_
+* `Examples <http://yaml.readthedocs.org/en/latest/example.html>`_
+* `Differences with PyYAML <http://yaml.readthedocs.org/en/latest/pyyaml.html>`_
+
+.. image:: https://readthedocs.org/projects/yaml/badge/?version=stable
+   :target: https://yaml.readthedocs.org/en/stable
+
+ChangeLog
+=========
+
+::
+
+  0.11.15 (2016-XX-XX):
+    - Change to prevent FutureWarning in NumPy, as reported by tgehring
+    ("comparison to None will result in an elementwise object comparison in the future")
+
+  0.11.14 (2016-07-06):
+    - fix preserve_quotes missing on original Loaders (as reported
+      by Leynos, bitbucket issue 38)
+
+  0.11.13 (2016-07-06):
+    - documentation only, automated linux wheels
+
+  0.11.12 (2016-07-06):
+    - added support for roundtrip of single/double quoted scalars using:
+      ruamel.yaml.round_trip_load(stream, preserve_quotes=True)
+
+  0.11.0 (2016-02-18):
+    - RoundTripLoader loads 1.2 by default (no sexagesimals, 012 octals nor
+      yes/no/on/off booleans

lib/spack/external/ruamel/yaml/__init__.py

@@ -0,0 +1,85 @@
+# coding: utf-8
+
+from __future__ import print_function
+from __future__ import absolute_import
+
+# install_requires of ruamel.base is not really required but the old
+# ruamel.base installed __init__.py, and thus a new version should
+# be installed at some point
+
+_package_data = dict(
+    full_package_name="ruamel.yaml",
+    version_info=(0, 11, 15),
+    author="Anthon van der Neut",
+    author_email="a.van.der.neut@ruamel.eu",
+    description="ruamel.yaml is a YAML parser/emitter that supports roundtrip preservation of comments, seq/map flow style, and map key order",  # NOQA
+    entry_points=None,
+    install_requires=dict(
+        any=[],
+        py26=["ruamel.ordereddict"],
+        py27=["ruamel.ordereddict"]
+    ),
+    ext_modules=[dict(
+        name="_ruamel_yaml",
+        src=["ext/_ruamel_yaml.c", "ext/api.c", "ext/writer.c", "ext/dumper.c",
+                "ext/loader.c", "ext/reader.c", "ext/scanner.c", "ext/parser.c",
+                "ext/emitter.c"],
+        lib=[],
+        # test='#include "ext/yaml.h"\n\nint main(int argc, char* argv[])\n{\nyaml_parser_t parser;\nparser = parser;  /* prevent warning */\nreturn 0;\n}\n'  # NOQA
+        )
+    ],
+    classifiers=[
+        "Programming Language :: Python :: 2.6",
+        "Programming Language :: Python :: 2.7",
+        "Programming Language :: Python :: 3.3",
+        "Programming Language :: Python :: 3.4",
+        "Programming Language :: Python :: 3.5",
+        "Programming Language :: Python :: Implementation :: CPython",
+        "Programming Language :: Python :: Implementation :: PyPy",
+        "Programming Language :: Python :: Implementation :: Jython",
+        "Topic :: Software Development :: Libraries :: Python Modules",
+        "Topic :: Text Processing :: Markup"
+    ],
+    windows_wheels=True,
+    read_the_docs='yaml',
+    many_linux='libyaml-devel',
+)
+
+
+# < from ruamel.util.new import _convert_version
+def _convert_version(tup):
+    """create a PEP 386 pseudo-format conformant string from tuple tup"""
+    ret_val = str(tup[0])  # first is always digit
+    next_sep = "."  # separator for next extension, can be "" or "."
+    for x in tup[1:]:
+        if isinstance(x, int):
+            ret_val += next_sep + str(x)
+            next_sep = '.'
+            continue
+        first_letter = x[0].lower()
+        next_sep = ''
+        if first_letter in 'abcr':
+            ret_val += 'rc' if first_letter == 'r' else first_letter
+        elif first_letter in 'pd':
+            ret_val += '.post' if first_letter == 'p' else '.dev'
+    return ret_val
+
+
+# <
+version_info = _package_data['version_info']
+__version__ = _convert_version(version_info)
+
+del _convert_version
+
+try:
+    from .cyaml import *                               # NOQA
+    __with_libyaml__ = True
+except (ImportError, ValueError):  # for Jython
+    __with_libyaml__ = False
+
+
+# body extracted to main.py
+try:
+    from .main import *                               # NOQA
+except ImportError:
+    from ruamel.yaml.main import *                               # NOQA