Move the test for buffer-local variables

The "ale#handlers#sh#GetShellType()" function currently falls back
to the file type without checking for buffer-local variables first.
This causes the function to return "sh" even when a script is known
by Vim to be a script of a more specific type (e.g., "bash").

The "ale#handlers#shellcheck#GetDialectArgument()" function then
erroneously uses this type even though a more fitting type should be
used instead.  Files without a "#!" line will be of type "sh" even
though they may have a ".bash" suffix.

This commit fixes the problem by checking for buffer-local shell
type variables (set by Vim) before falling back to the file type.

autoload/ale/handlers/sh.vim

@@ -11,6 +11,17 @@ function! ale#handlers#sh#GetShellType(buffer) abort
         let l:command = substitute(l:shebang, ' --\?[a-zA-Z0-9]\+', '', 'g')
     endif
 
+    " With no shebang line, attempt to use Vim's buffer-local variables.
+    if l:command is# ''
+        if getbufvar(a:buffer, 'is_bash', 0)
+            let l:command = 'bash'
+        elseif getbufvar(a:buffer, 'is_sh', 0)
+            let l:command = 'sh'
+        elseif getbufvar(a:buffer, 'is_kornshell', 0)
+            let l:command = 'ksh'
+        endif
+    endif
+
     " If we couldn't find a shebang, try the filetype
     if l:command is# ''
         let l:command = &filetype

autoload/ale/handlers/shellcheck.vim

@@ -13,15 +13,6 @@ function! ale#handlers#shellcheck#GetDialectArgument(buffer) abort
         return l:shell_type
     endif
 
-    " If there's no hashbang, try using Vim's buffer variables.
-    if getbufvar(a:buffer, 'is_bash', 0)
-        return 'bash'
-    elseif getbufvar(a:buffer, 'is_sh', 0)
-        return 'sh'
-    elseif getbufvar(a:buffer, 'is_kornshell', 0)
-        return 'ksh'
-    endif
-
     return ''
 endfunction