Switch releases to a single multi-pex. (#698)

Fixes #654

RELEASE.rst

@@ -16,18 +16,15 @@ local commit:
 ::
 
     $ git log --stat -1
-    commit 47c26d746046a8ab21bd3cb3bb782ce5f018a369 (HEAD -> master, tag: v1.4.7, origin/master, origin/HEAD)
+    commit 8ffb208eb8cc597a4a486b212e0f6d3a12416a09 (HEAD -> master, tag: v1.6.5, origin/master, origin/HEAD)
     Author: John Sirois <[email protected]>
-    Date:   Tue Sep 25 16:06:26 2018 -0600
+    Date:   Fri Mar 29 17:53:00 2019 -0700
 
-        Prepare the 1.4.7 release. (#556)
-    
-        Fixes #555
+        Prepare the 1.6.5 release. (#697)
 
      CHANGES.rst    | 8 ++++++++
      pex/version.py | 2 +-
-     setup.py       | 1 +
-     3 files changed, 10 insertions(+), 1 deletion(-)
+     2 files changed, 9 insertions(+), 1 deletion(-)
 
 Push to Master
 --------------
@@ -36,7 +33,7 @@ Tag, push and watch Travis CI go green:
 
 ::
 
-    $ git tag --sign -am 'Release 1.4.7' v1.4.7
+    $ git tag --sign -am 'Release 1.6.5' v1.6.5
     $ git push --tags origin HEAD
 
 PyPI Release
@@ -57,7 +54,7 @@ Dogfood
     $ pip install --no-cache-dir --upgrade pex
     ...
     $ pex --version
-    pex 1.4.7
+    pex 1.6.5
 
 Github Release
 ==============
@@ -67,49 +64,36 @@ Prepare binary assets
 
 ::
 
-    $ tox -e py27-package
+    $ tox -e package
     ...
-    $ ./dist/pex27 --version
-    pex27 1.4.7
-
-    $ tox -e py37-package
-    ...
-    $ ./dist/pex37 --version
-    pex36 1.4.7
+    $ ./dist/pex --version
+    pex 1.6.5
 
 Craft the Release
 -----------------
 
 Open a tab on prior release as a template:
 
--  https://github.com/pantsbuild/pex/releases/edit/v1.4.6
+-  https://github.com/pantsbuild/pex/releases/edit/v1.6.4
 
 Open a tab to construct the current:
 
--  https://github.com/pantsbuild/pex/releases/new?tag=v1.4.7
+-  https://github.com/pantsbuild/pex/releases/new?tag=v1.6.5
 
-1. Use "Release <VERSION>" as the release name (e.g. "Release 1.4.7")
+1. Use "Release <VERSION>" as the release name (e.g. "Release 1.6.5")
 2. Copy and paste the most recent CHANGES.rst section.
 3. Adapt the syntax from RestructuredText to Markdown (e.g. ``#ID <links>`` -> ``#ID``).
-4. Upload both the ``pex27`` and ``pex37`` artifacts.
+4. Upload the ``pex`` artifact.
 
 Check your work
 ---------------
 
 ::
 
-    $ curl -L https://github.com/pantsbuild/pex/releases/download/v1.4.7/pex27 -O
+    $ curl -L https://github.com/pantsbuild/pex/releases/download/v1.6.5/pex -O
       % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                      Dload  Upload   Total   Spent    Left  Speed
     100   578    0   578    0     0    525      0 --:--:--  0:00:01 --:--:--   525
     100 1450k  100 1450k    0     0   128k      0  0:00:11  0:00:11 --:--:--  139k
-    $ ./pex27 --version
-    pex27 1.4.7
-
-    $ curl -L https://github.com/pantsbuild/pex/releases/download/v1.4.7/pex37 -O
-      % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
-                                     Dload  Upload   Total   Spent    Left  Speed
-    100   578    0   578    0     0    296      0 --:--:--  0:00:01 --:--:--   296
-    100 1406k  100 1406k    0     0   131k      0  0:00:10  0:00:10 --:--:--  256k
-    $ ./pex37 --version
-    pex37 1.4.7
+    $ ./pex --version
+    pex 1.6.5

tox.ini

@@ -180,20 +180,17 @@ commands = pex {posargs:}
 [testenv:py37-run]
 commands = pex {posargs:}
 
-[testenv:py27-package]
-commands = pex --cache-dir {envtmpdir}/buildcache requests . -o dist/pex27 -e pex.bin.pex:main -v
-
-[testenv:py34-package]
-commands = pex --cache-dir {envtmpdir}/buildcache requests . -o dist/pex34 -e pex.bin.pex:main -v
-
-[testenv:py35-package]
-commands = pex --cache-dir {envtmpdir}/buildcache requests . -o dist/pex35 -e pex.bin.pex:main -v
-
-[testenv:py36-package]
-commands = pex --cache-dir {envtmpdir}/buildcache requests . -o dist/pex36 -e pex.bin.pex:main -v
-
-[testenv:py37-package]
-commands = pex --cache-dir {envtmpdir}/buildcache requests . -o dist/pex37 -e pex.bin.pex:main -v
+[testenv:package]
+# TODO(John Sirois): Include subprocess32 when #415, #658 and #694 are resolved.
+commands =
+  pex -v \
+    --cache-dir {envtmpdir}/buildcache \
+    --interpreter-constraint=">=3.4,<4" \
+    --interpreter-constraint="==2.7.*" \
+    --python-shebang="/usr/bin/env python" \
+    -o dist/pex \
+    -c pex \
+    requests .
 
 # Would love if you didn't have to enumerate environments here :-\
 [testenv:py27]