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

The changed behavior of sdist in 2.7 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 (d29399100973 by Tarek and
f7639dcdffc3 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 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.  I also removed a stanza in the docs that
was forgotten in Tarek’s first changeset.

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, 17 insertions, 12 deletions

diff --git a/Doc/distutils/sourcedist.rst b/Doc/distutils/sourcedist.rst
index fc860de..a9858d0 100644
--- a/Doc/distutils/sourcedist.rst
+++ b/Doc/distutils/sourcedist.rst
@@ -111,12 +111,22 @@ per line, regular files (or symlinks to them) only.  If you do supply your own
 :file:`MANIFEST`, you must specify everything: the default set of files
 described above does not apply in this case.
 
-.. versionadded:: 2.7
+.. versionchanged:: 2.7
+   An existing generated :file:`MANIFEST` will be regenerated without
+   :command:`sdist` comparing its modification time to the one of
+   :file:`MANIFEST.in` or :file:`setup.py`.
+
+.. versionchanged:: 2.7.1
    :file:`MANIFEST` files start with a comment indicating they are generated.
    Files without this comment are not overwritten or removed.
 
+.. versionchanged:: 2.7.3
+   :command:`sdist` will read a :file:`MANIFEST` file if no :file:`MANIFEST.in`
+   exists, like it did before 2.7.
+
 See :ref:`manifest_template` section for a syntax reference.
 
+
 .. _manifest-options:
 
 Manifest-related options
@@ -124,16 +134,16 @@ Manifest-related options
 
 The normal course of operations for the :command:`sdist` command is as follows:
 
-* if the manifest file, :file:`MANIFEST` doesn't exist, read :file:`MANIFEST.in`
-  and create the manifest
+* if the manifest file (:file:`MANIFEST` by default) exists and the first line
+  does not have a comment indicating it is generated from :file:`MANIFEST.in`,
+  then it is used as is, unaltered
+
+* if the manifest file doesn't exist or has been previously automatically
+  generated, read :file:`MANIFEST.in` and create the manifest
 
 * if neither :file:`MANIFEST` nor :file:`MANIFEST.in` exist, create a manifest
   with just the default file set
 
-* if either :file:`MANIFEST.in` or the setup script (:file:`setup.py`) are more
-  recent than :file:`MANIFEST`, recreate :file:`MANIFEST` by reading
-  :file:`MANIFEST.in`
-
 * use the list of files now in :file:`MANIFEST` (either just generated or read
   in) to create the source distribution archive(s)
 
@@ -271,8 +281,3 @@ character, and ``[range]`` matches any of the characters in *range* (e.g.,
 ``a-z``, ``a-zA-Z``, ``a-f0-9_.``).  The definition of "regular filename
 character" is platform-specific: on Unix it is anything except slash; on Windows
 anything except backslash or colon.
-
-.. versionchanged:: 2.7
-    An existing generated :file:`MANIFEST` will be regenerated without
-    :command:`sdist` comparing its modification time to the one of
-    :file:`MANIFEST.in` or :file:`setup.py`.