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tst/editor/vim_feature_test.vim

@@ -20,6 +20,11 @@
 "
 " Writes PASS/FAIL lines to $KT_OUT; exits nonzero if anything failed.
 
+" The buffer text below is UTF-8 (the umlauts of the multibyte case).  Vim
+" takes 'encoding' from the locale, and under a C locale that is latin1,
+" where each umlaut is two characters and the jump lands two columns short
+" -- a failure of this file, not of the plugin (TODO 78, 2026-10-19).
+set encoding=utf-8
 let s:results = []
 function! s:Check(name, ok, ...) abort
   let detail = (a:ok || !a:0) ? '' : ' -- ' . string(a:1)