patch 8.0.1638: popup test fails depending on environment variable

Problem:    Popup test fails depending on environment variable.
Solution:   Reset $COLORFGBG when running Vim in a terminal. (closes #2693)
diff --git a/src/version.c b/src/version.c
index 0249efb..3a5bcfb 100644
--- a/src/version.c
+++ b/src/version.c
@@ -767,6 +767,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1638,
+/**/
     1637,
 /**/
     1636,