treewide: remove redundant quotes

pkgs/build-support/fetchgit/default.nix

@@ -52,7 +52,7 @@ else
 stdenvNoCC.mkDerivation {
   inherit name;
   builder = ./builder.sh;
-  fetcher = "${./nix-prefetch-git}";  # This must be a string to ensure it's called with bash.
+  fetcher = ./nix-prefetch-git;  # This must be a string to ensure it's called with bash.
   nativeBuildInputs = [git];
 
   outputHashAlgo = "sha256";

pkgs/build-support/fetchgit/private.nix

@@ -4,7 +4,7 @@
     else null;
 
   GIT_SSH = let
-    config = ''${let
+    config = let
         sshConfigFile = if (builtins.tryEval <ssh-config-file>).success
           then <ssh-config-file>
           else builtins.trace ''
@@ -14,7 +14,7 @@
 
             You may need StrictHostKeyChecking=no in the config file. Since ssh will refuse to use a group-readable private key, if using build-users you will likely want to use something like IdentityFile /some/directory/%u/key and have a directory for each build user accessible to that user.
           '' "/var/lib/empty/config";
-      in builtins.toString sshConfigFile}'';
+      in builtins.toString sshConfigFile;
 
     ssh-wrapped = runCommand "fetchgit-ssh" {
       nativeBuildInputs = [ makeWrapper ];