[PATCH 0/6] Forwarding Sverre's "merge --ff=<allow,only,never>" series

A few weeks ago Sverre's "merge --ff=<allow,only,never>" series was
re-sent to the list but as 6 attachments to a single mail.  The format was
unfortunate and nobody seems to have bothered to read nor comment on.

I think the early patches in the series are at least worth keeping and the
overall series deserves some attention from the list, so I am re-injecting
them in format that can hopefully be commented on and tried out as a
public service ;-) I am tempted to apply up to [3/6] after another round
of reading myself.

A few minor nits I already have:

 [2/6]

"diff -u" in verify_diff() should be "test_cmp":

@@ -254,7 +254,7 @@
 +}
 +
 +verify_diff() {
-+      if ! diff -u "$1" "$2"
++      if ! test_cmp "$1" "$2"
 +      then
 +              echo "$3"
 +              false

 [3/6] 

The argument to --ff is optional (log message):

---ff now takes an argument allowing --ff to be written
-as --ff=allow and -no-ff to be written as --ff=never.
-This change allow other fast forward options to be
-introduced later.
-
-See the documentation for a further explanation of these options.
+The --ff flag now takes an optional argument, allowing --ff to be
+written as --ff=allow and -no-ff to be written as --ff=never. This
+allows other fast forward options to be introduced later.

Also, you usually should not say 'see doc for details' in commit log, as
it does not help anybody.  Either you convince others that your patch is
worth reading by your commit log message alone, or you don't.

Grammar.

 +The first merge of topicA or the only merge of topicB would have
-+resulted in a fast forward without '--ff=never'.  Topic A consist of
++resulted in a fast forward without '--ff=never'.  Topic A consists of
 +those commits that can be reached from master^2 without passing

 [4/6]

Grammar.

 +# Find reduced parents
-+# The following variables are set as follow:
++# The following variables are set as follows:
 +#   reduced_parents: The reduced parents of those specified on the
 command line.

 [6/6]

Commit log:

 instead of a real merge.  This option can then be used to
 avoid an accidental merge.
 
-See the documentation for further details.
-