Format partition only if newly created

lib/modules/partition.nix

@@ -123,6 +123,14 @@
 
                   create = lib.strings.concatLines [
                     (appendScript "${toString index}: \"$(${sizeOption})\" type=${mkType type}")
+                    # Wait for partition to be detected
+                    ''
+                      while true;
+                      do
+                        [ -b ${partVar} ] && break;
+                      done;
+                    ''
+                    "sudo ${formatScripts.${format}}"
                   ];
 
                   fallback = ''
@@ -132,17 +140,9 @@
                     fi
                   '';
                 in [
-                  (if keepExisting then fallback else create)
                   ''local diskPath="$(find -L /dev/disk/by-diskseq -samefile ${diskVar})"''
                   ''local ${partVarName}="$diskPath-part${toString index}"''
-                  # Wait for partition to be detected
-                  ''
-                    while true;
-                    do
-                      [ -b ${partVar} ] && break;
-                    done;
-                  ''
-                  "sudo ${formatScripts.${format}}"
+                  (if keepExisting then fallback else create)
                   "sudo ${labelScripts.${format} label}"
                 ])
               partitions)