Fix the release script. (#6629)

The latest version of wheel (0.32.1, just released) no longer writes
the metadata.json file (see pypa/wheel#195).
Instead, we must now read the version from the METADATA file.

This change also tightens up the release docs a bit.

src/docs/release.md

@@ -51,9 +51,7 @@ script fail:
 
   - **Get your pypi account added as an `owner` for all pantsbuild.pants packages.**
 
-    You can ask any one of the [Owners](#owners) listed below to do this.
-    Once this is done and you've performed your 1st release, add yourself to
-    the [Owners](#owners) section below.
+    You can ask any one of the current [Owners](#owners) to do this.
 
   - **Configure your pypi credentials locally in `~/.pypirc`**
 
@@ -194,39 +192,21 @@ if the tag for the prior release (eg: release_0.0.33)
     :::bash
     $ ./build-support/bin/contributors.sh -s <tag>
 
-Listing Packages and Owners
+<a name="owners"></a>Listing Packages and Owners
 ------
 
 The current list of packages can be obtained via :
 
     :::bash
     $ ./build-support/bin/release.sh -l
 
-Right now that's:
-
-- pantsbuild.pants
-- pantsbuild.pants.contrib.avro
-- pantsbuild.pants.contrib.buildgen
-- pantsbuild.pants.contrib.codeanalysis
-- pantsbuild.pants.contrib.confluence
-- pantsbuild.pants.contrib.cpp
-- pantsbuild.pants.contrib.errorprone
-- pantsbuild.pants.contrib.findbugs
-- pantsbuild.pants.contrib.go
-- pantsbuild.pants.contrib.googlejavaformat
-- pantsbuild.pants.contrib.jax_ws
-- pantsbuild.pants.contrib.mypy
-- pantsbuild.pants.contrib.node
-- pantsbuild.pants.contrib.python.checks
-- pantsbuild.pants.contrib.scalajs
-- pantsbuild.pants.contrib.scrooge
-- pantsbuild.pants.contrib.thrifty
-- pantsbuild.pants.testinfra
-
 You can run the following to get a full ownership roster for each
 package :
 
     :::bash
     $ ./build-support/bin/release.sh -o
 
+We generally expect all packages to have the same set of owners, which you can 
+view [here](https://pypi.org/project/pantsbuild.pants/).
+
 [needs-cherrypick]: https://github.com/pantsbuild/pants/pulls?q=is%3Apr+label%3Aneeds-cherrypick

src/python/pants/releases/reversion.py

@@ -9,8 +9,8 @@
 import fnmatch
 import glob
 import hashlib
-import json
 import os
+import re
 import zipfile
 from builtins import open, str
 
@@ -89,6 +89,11 @@ def rewrite_record_file(workspace, src_record_file, mutated_file_tuples):
   safe_file_dump(os.path.join(workspace, dst_record_file), '\r\n'.join(output_records) + '\r\n', binary_mode=False)
 
 
+# The wheel METADATA file will contain a line like: `Version: 1.11.0.dev3+7951ec01`.
+# We don't parse the entire file because it's large (it contains the entire release notes history).
+_version_re = re.compile('Version: (?P<version>\S+)')
+
+
 def reversion(args):
   with temporary_dir() as workspace:
     # Extract the input.
@@ -100,10 +105,17 @@ def reversion(args):
     dist_info_dir = locate_dist_info_dir(workspace)
     record_file = os.path.join(dist_info_dir, 'RECORD')
 
-    # Load metadata for the input whl.
-    with open(os.path.join(workspace, dist_info_dir, 'metadata.json'), 'r') as info:
-      metadata = json.load(info)
-    input_version = metadata['version']
+    # Get version from the input whl's metadata.
+    input_version = None
+    metadata_file = os.path.join(workspace, dist_info_dir, 'METADATA')
+    with open(metadata_file, 'r') as info:
+      for line in info:
+        mo = _version_re.match(line)
+        if mo:
+          input_version = mo.group('version')
+          break
+    if not input_version:
+      raise Exception('Could not find `Version:` line in {}'.format(metadata_file))
 
     # Rewrite and move all files (including the RECORD file), recording which files need to be
     # re-fingerprinted due to content changes.