text: Null-terminate a string if we've been gouging it

src/buf_text.c

diff --git a/src/buf_text.c b/src/buf_text.c
index 8d2b141..cead599 100644
--- a/src/buf_text.c
+++ b/src/buf_text.c
@@ -143,6 +143,7 @@
 		tgt->ptr[tgt->size++] = '\n';
 	}
 
+	tgt->ptr[tgt->size] = '\0';
 	return git_buf_put(tgt, scan, end - scan);
 }