Clear have_next_byte when the source is closed.

From PR #555

lib/zip_source_close.c

diff --git a/lib/zip_source_close.c b/lib/zip_source_close.c
index 4603c6d..10fdc33 100644
--- a/lib/zip_source_close.c
+++ b/lib/zip_source_close.c
@@ -43,6 +43,8 @@
 
     src->open_count--;
     if (src->open_count == 0) {
+        src->have_next_byte = false;
+
         _zip_source_call(src, NULL, 0, ZIP_SOURCE_CLOSE);
 
         if (ZIP_SOURCE_IS_LAYERED(src)) {

lib/zip_source_open.c

diff --git a/lib/zip_source_open.c b/lib/zip_source_open.c
index 97c2378..4a11199 100644
--- a/lib/zip_source_open.c
+++ b/lib/zip_source_open.c
@@ -65,10 +65,13 @@
         }
     }
 
+    /* TODO: Move the next four lines to into the else branch above, or better yet to zip_source_close()?
+       They should probably only happen when ZIP_SOURCE_IS_OPEN_READING(src) changes, so other references that have the source open are not affected. */
     src->eof = false;
     src->had_read_error = false;
     _zip_error_clear(&src->error);
     src->bytes_read = 0;
+
     src->open_count++;
 
     return 0;