Update bash

Changes:

- https://github.com/tianon/docker-bash/commit/7902e2b: Update to commit 4c39fa08abaa7e9b23c1760a5a3be893cbd33aef

library/bash

@@ -3,9 +3,9 @@
 Maintainers: Tianon Gravi <[email protected]> (@tianon)
 GitRepo: https://github.com/tianon/docker-bash.git
 
-Tags: devel-20190731, devel
+Tags: devel-20190802, devel
 Architectures: amd64, arm32v6, arm32v7, arm64v8, i386, ppc64le, s390x
-GitCommit: 6eb9ff4b3b7c41c4199900d0981b5c36f4def83e
+GitCommit: 7902e2b9b40bf7d6ae61cce9637338e957af538b
 Directory: devel
 
 Tags: 5.0.7, 5.0, 5, latest