Fix regression with distutils MANIFEST handing (#11104, #8688).

The changed behavior of sdist in 3.1 broke packaging for projects that
wanted to use a manually-maintained MANIFEST file (instead of having a
MANIFEST.in template and letting distutils generate the MANIFEST).

The fixes that were committed for #8688 (76643c286b9f by Tarek and
d54da9248ed9 by me) did not fix all issues exposed in the bug report,
and also added one problem: the MANIFEST file format gained comments,
but the read_manifest method was not updated to handle (i.e. ignore)
them.  This changeset should fix everything; the tests have been
expanded and I successfully tested the 2.7 version with Mercurial, which
suffered from this regression.

I have grouped the versionchanged directives for these bugs in one place
and added micro version numbers to help users know the quirks of the
exact version they’re using.

Initial report, thorough diagnosis and patch by John Dennis, further
work on the patch by Stephen Thorne, and a few edits and additions by
me.

1 files changed, 29 insertions, 19 deletions

diff --git a/Lib/distutils/command/sdist.py b/Lib/distutils/command/sdist.py
index 48cb26b..21ea61d 100644
--- a/Lib/distutils/command/sdist.py
+++ b/Lib/distutils/command/sdist.py
@@ -174,14 +174,20 @@ class sdist(Command):
         reading the manifest, or just using the default file set -- it all
         depends on the user's options.
         """
-        # new behavior:
+        # new behavior when using a template:
         # the file list is recalculated everytime because
         # even if MANIFEST.in or setup.py are not changed
         # the user might have added some files in the tree that
         # need to be included.
         #
-        #  This makes --force the default and only behavior.
+        #  This makes --force the default and only behavior with templates.
         template_exists = os.path.isfile(self.template)
+        if not template_exists and self._manifest_is_not_generated():
+            self.read_manifest()
+            self.filelist.sort()
+            self.filelist.remove_duplicates()
+            return
+
         if not template_exists:
             self.warn(("manifest template '%s' does not exist " +
                         "(using default file list)") %
@@ -336,23 +342,28 @@ class sdist(Command):
         by 'add_defaults()' and 'read_template()') to the manifest file
         named by 'self.manifest'.
         """
-        if os.path.isfile(self.manifest):
-            fp = open(self.manifest)
-            try:
-                first_line = fp.readline()
-            finally:
-                fp.close()
-
-            if first_line != '# file GENERATED by distutils, do NOT edit\n':
-                log.info("not writing to manually maintained "
-                         "manifest file '%s'" % self.manifest)
-                return
+        if self._manifest_is_not_generated():
+            log.info("not writing to manually maintained "
+                     "manifest file '%s'" % self.manifest)
+            return
 
         content = self.filelist.files[:]
         content.insert(0, '# file GENERATED by distutils, do NOT edit')
         self.execute(file_util.write_file, (self.manifest, content),
                      "writing manifest file '%s'" % self.manifest)
 
+    def _manifest_is_not_generated(self):
+        # check for special comment used in 3.1.3 and higher
+        if not os.path.isfile(self.manifest):
+            return False
+
+        fp = open(self.manifest)
+        try:
+            first_line = fp.readline()
+        finally:
+            fp.close()
+        return first_line != '# file GENERATED by distutils, do NOT edit\n'
+
     def read_manifest(self):
         """Read the manifest file (named by 'self.manifest') and use it to
         fill in 'self.filelist', the list of files to include in the source
@@ -360,12 +371,11 @@ class sdist(Command):
         """
         log.info("reading manifest file '%s'", self.manifest)
         manifest = open(self.manifest)
-        while True:
-            line = manifest.readline()
-            if line == '':              # end of file
-                break
-            if line[-1] == '\n':
-                line = line[0:-1]
+        for line in manifest:
+            # ignore comments and blank lines
+            line = line.strip()
+            if line.startswith('#') or not line:
+                continue
             self.filelist.append(line)
         manifest.close()