Close p->mwf.fd only if necessary

This fixes a regression introduced in revision 9d2f841a.

Signed-off-by: Sven Strickroth <email@cs-ware.de>

src/pack.c

@@ -822,7 +822,7 @@ void git_packfile_free(struct git_pack_file *p)
 
 	git_mwindow_free_all(&p->mwf);
 
-	if (p->mwf.fd != -1)
+	if (p->mwf.fd >= 0)
 		p_close(p->mwf.fd);
 
 	pack_index_free(p);
@@ -905,6 +905,7 @@ static int packfile_open(struct git_pack_file *p)
 cleanup:
 	giterr_set(GITERR_OS, "Invalid packfile '%s'", p->pack_name);
 
+	if (p->mwf.fd >= 0)
 		p_close(p->mwf.fd);
 	p->mwf.fd = -1;