nixpkgs/elvish: fix yadm shim

.config/nixpkgs/elvish/lib/config.elv

@@ -11,7 +11,7 @@ edit:add-var ls~ { |@a|
 if (has-external yadm) {
   set-env YADM_OVERRIDE_REPO ~/.dotfiles
 } else {
-  edit:add-var yadm~ { |@a| git --git-dir=~/.dotfiles/ --work-tree=~ $@a }
+  edit:add-var yadm~ { |@a| git --git-dir=$E:HOME/.dotfiles/ --work-tree=$E:HOME $@a }
 }
 
 if (has-external delta) {