Add cW map as commit --fixup=reword:

References: #2369

Author: tpope

autoload/fugitive.vim

@@ -7917,6 +7917,7 @@ function! s:MapGitOps(is_ftplugin) abort
   exe s:Map('n', 'cc', ':<C-U>Git commit<CR>', '<silent>', ft)
   exe s:Map('n', 'ce', ':<C-U>Git commit --amend --no-edit<CR>', '<silent>', ft)
   exe s:Map('n', 'cw', ':<C-U>Git commit --amend --only<CR>', '<silent>', ft)
+  exe s:Map('n', 'cW', ':<C-U>Git commit --fixup=reword:<C-R>=<SID>SquashArgument()<CR>', '', ft)
   exe s:Map('n', 'cva', ':<C-U>tab Git commit -v --amend<CR>', '<silent>', ft)
   exe s:Map('n', 'cvc', ':<C-U>tab Git commit -v<CR>', '<silent>', ft)
   exe s:Map('n', 'cRa', ':<C-U>Git commit --reset-author --amend<CR>', '<silent>', ft)

doc/fugitive.txt

@@ -465,15 +465,18 @@ Commit maps ~
 
 cc                      Create a commit.
 
+cvc                     Create a commit with -v.
+
 ca                      Amend the last commit and edit the message.
 
+cva                     Amend the last commit with -v.
+
 ce                      Amend the last commit without editing the message.
 
 cw                      Reword the last commit.
 
-cvc                     Create a commit with -v.
-
-cva                     Amend the last commit with -v
+cW                      Create an `amend!` commit that rewords the commit
+                        under the cursor.
 
 cf                      Create a `fixup!` commit for the commit under the
                         cursor.