plugin/magit.vim: fix template commit duplicate on refresh

On refresh, fill commit message my default one if empty, or current one, not both

fix #135

plugin/magit.vim

@@ -185,14 +185,13 @@ function! s:mg_get_commit_section()
 			silent! call magit#utils#system("GIT_EDITOR=/bin/false " .
 						\ g:magit_git_cmd . " -c commit.verbose=no commit --amend -e 2> /dev/null")
 		endif
-		if ( filereadable(git_dir . 'COMMIT_EDITMSG') )
+		if ( !empty(b:magit_current_commit_msg) )
+			silent put =b:magit_current_commit_msg
+		elseif ( filereadable(git_dir . 'COMMIT_EDITMSG') )
 			let comment_char=magit#git#get_config("core.commentChar", '#')
 			let commit_msg=magit#utils#join_list(filter(readfile(git_dir . 'COMMIT_EDITMSG'), 'v:val !~ "^' . comment_char . '"'))
 			silent put =commit_msg
 		endif
-		if ( !empty(b:magit_current_commit_msg) )
-			silent put =b:magit_current_commit_msg
-		endif
 		silent put =''
 		silent put =''
 	endif