Fix reading multi-line quoted here-documents

* geesh/lexer.scm (get-quoted-here-doc): Use the correct line-reading
procedure when looping.
* tests/lexer.scm: Add test.

geesh/lexer.scm

@@ -561,7 +561,7 @@ marks the end of the here-document."
         (let ((line* (string-trim-right line #\newline)))
           (if (string=? line* end)
               `(<sh-quote> ,(string-concatenate-reverse acc))
-              (loop (get-line port) (cons line acc)))))))
+              (loop (read-line port 'concat) (cons line acc)))))))
 
 (define (get-unquoted-here-doc end port)
   "Get an unquoted here-document string from @var{port}, where

tests/lexer.scm

@@ -299,6 +299,10 @@
   '(HERE-DOC (0 . 7) (<sh-quote> "$x\n"))
   (get-here-doc* "eof" "$x\neof" #:quoted? #t))
 
+(test-equal "Lexes a multi-line quoted here-document"
+  '(HERE-DOC (0 . 8) (<sh-quote> "a\nb\n"))
+  (get-here-doc* "eof" "a\nb\neof" #:quoted? #t))
+
 (test-equal "Lexes a here-document with tab trimming"
   '(HERE-DOC (0 . 15) (<sh-quote> "foo\nbar\n"))
   (get-here-doc* "eof" "\tfoo\n\tbar\n\teof" #:trim-tabs? #t))