Use g:ledger_main instead of % in #entry().

Author: Lifepillar

autoload/ledger.vim

@@ -399,7 +399,7 @@ func! ledger#entry()
   let l = line('.') - 1 " Insert transaction at the current line (i.e., below the line above the current one)
   let query = getline('.')
   normal "_dd
-  exec l . 'read !' g:ledger_bin '-f' shellescape(expand('%')) 'entry' shellescape(query)
+  exec l . 'read !' g:ledger_bin '-f' shellescape(expand(g:ledger_main)) 'entry' shellescape(query)
 endfunc
 
 " Report generation {{{1