Avoid losing work in funced when no changes between parse errors

From the inital dd69ca5 commit that started checking if the file was modified
the initial checksum to compare against has been updated in the loop, causing
funced to lose work silently if you get a parse error, can't find the issue,
and want to look at the error message again.

Closes #12663

CHANGELOG.rst

@@ -20,6 +20,7 @@ Other improvements
 - History is no longer corrupted with NUL bytes when fish receives SIGTERM or SIGHUP (:issue:`10300`).
 - :doc:`fish_update_completions <cmds/fish_update_completions>` now handles groff ``\X'...'`` device control escapes, fixing completion generation for man pages produced by help2man 1.50 and later (such as coreutils 9.10).
 - Improve user experience when removing history entries via the :doc:`web-based config <cmds/fish_config>`.
+- :doc:`funced <cmds/funced>` will no longer lose work if there are parse errors multiple times without new changes to the file
 
 For distributors and developers
 -------------------------------

share/functions/funced.fish

@@ -91,9 +91,8 @@ function funced --description 'Edit function definition'
     # Repeatedly edit until it either parses successfully, or the user cancels
     # If the editor command itself fails, we assume the user cancelled or the file
     # could not be edited, and we do not try again
+    set -l checksum (__fish_md5 "$tmpname")
     while true
-        set -l checksum (__fish_md5 "$tmpname")
-
         if not $editor $tmpname
             echo (_ "Editing failed or was cancelled")
         else