setup: include additional packages in py2exe distribution

I'm attempting to reproduce the Inno installers on my local
machine. As part of auditing differences between installer output,
I noticed that the existing Inno installers include various 3rd
party packages.

There is no mention of this in the build instructions nor on
the wiki. This must be something that is done by the installer
producer.

This commit teaches setup.py to include these 3rd party packages
in py2exe's library. After this change, I am able to produce
Inno installers that have a nearly identical set of Python
modules.

It's worth noting that pywin32 is included even though it
probably shouldn't be. But including it is necessary in order
to achieve parity with existing Inno installers.

Differential Revision: https://phab.mercurial-scm.org/D6064

setup.py

@@ -1240,8 +1240,20 b" setupversion = version.decode('ascii')"
 
 extra = {}
 
+py2exepackages = [
+    'hgdemandimport',
+    'hgext',
+    'email',
+    # implicitly imported per module policy
+    # (cffi wouldn't be used as a frozen exe)
+    'mercurial.cext',
+    #'mercurial.cffi',
+    'mercurial.pure',
+]
+
 if issetuptools:
     extra['python_requires'] = supportedpy
+
 if py2exeloaded:
     extra['console'] = [
         {'script':'hg',
@@ -1252,6 +1264,34 b' if py2exeloaded:'
     # put dlls in sub directory so that they won't pollute PATH
     extra['zipfile'] = 'lib/library.zip'
 
+    try:
+        import dulwich
+        dulwich.__version__
+        py2exepackages.append('dulwich')
+    except ImportError:
+        pass
+
+    try:
+        import keyring
+        keyring.util
+        py2exepackages.append('keyring')
+    except ImportError:
+        pass
+
+    try:
+        import pygments
+        pygments.__version__
+        py2exepackages.append('pygments')
+    except ImportError:
+        pass
+
+    try:
+        import pywintypes
+        pywintypes.TRUE
+        py2exepackages.append('pywintypes')
+    except ImportError:
+        pass
+
 if os.name == 'nt':
     # Windows binary file versions for exe/dll files must have the
     # form W.X.Y.Z, where W,X,Y,Z are numbers in the range 0..65535
@@ -1331,16 +1371,7 b" setup(name='mercurial',"
       distclass=hgdist,
       options={
           'py2exe': {
-              'packages': [
-                  'hgdemandimport',
-                  'hgext',
-                  'email',
-                  # implicitly imported per module policy
-                  # (cffi wouldn't be used as a frozen exe)
-                  'mercurial.cext',
-                  #'mercurial.cffi',
-                  'mercurial.pure',
-              ],
+              'packages': py2exepackages,
           },
           'bdist_mpkg': {
               'zipdist': False,