Recover the complicated situation after my bad merge

I made a mistake merge.  Reverting it in c778945806 undid the state
on master, but now I realize it crippled the git merge mechanism.
As the merge contained a mix of commits from `master..staging-next`
and other commits from `staging-next..staging`, it got the
`staging-next` branch into a state that was difficult to recover.

I reconstructed the "desired" state of staging-next tree by:
 - checking out the last commit of the problematic range: 4effe769e2
 - `git rebase -i --preserve-merges a8a018ddc0` - dropping the mistaken
   merge commit and its revert from that range (while keeping
   reapplication from 4effe769e2)
 - merging the last unaffected staging-next commit (803ca85c20)
 - fortunately no other commits have been pushed to staging-next yet
 - applying a diff on staging-next to get it into that state

pkgs/applications/version-management/git-and-tools/git/default.nix

@@ -22,7 +22,7 @@ assert sendEmailSupport -> perlSupport;
 assert svnSupport -> perlSupport;
 
 let
-  version = "2.28.0";
+  version = "2.29.0";
   svn = subversionClient.override { perlBindings = perlSupport; };
 
   gitwebPerlLibs = with perlPackages; [ CGI HTMLParser CGIFast FCGI FCGIProcManager HTMLTagCloud ];
@@ -34,7 +34,7 @@ stdenv.mkDerivation {
 
   src = fetchurl {
     url = "https://www.kernel.org/pub/software/scm/git/git-${version}.tar.xz";
-    sha256 = "17a311vzimqn1glc9d7x82rhb1mb81m5rr4g8xji8idaafid39fz";
+    sha256 = "KEMtmVJXxGJv4PsgkfWI327tmOlXFBnnLIO8Izcua4k=";
   };
 
   outputs = [ "out" ] ++ stdenv.lib.optional withManual "doc";