Use master of pygresql due to bug in 5.1.2

We encounted a bug in escaping dbname and connection options in pygresql
5.1.2, which we submitted a patch for here:
https://github.com/PyGreSQL/PyGreSQL/pull/40

This has been merged, but it will take time to be added to a tagged
release. For this reason, we have downloaded the source using this
commit,
https://github.com/PyGreSQL/PyGreSQL/commit/b1e040e989b5b1b75f42c1103562bfe8f09f93c3
to install.
Co-authored-by: NTyler Ramer <tramer@pivotal.io>
Co-authored-by: NJamie McAtamney <jmcatamney@pivotal.io>

.gitmodules

@@ -4,8 +4,8 @@
 	branch = pgbouncer_1_8_1
 [submodule "gpMgmt/bin/pythonSrc/ext"]
 	path = gpMgmt/bin/pythonSrc/ext
-	url = https://github.com/tylarb/pythonsrc-ext.git
-	branch = pygresql
+	url = https://github.com/greenplum-db/pythonsrc-ext.git
+	branch = master
 [submodule "gpcontrib/gpcloud/test/googletest"]
 	path = gpcontrib/gpcloud/test/googletest
 	url = https://github.com/google/googletest.git

gpMgmt/bin/Makefile

@@ -71,7 +71,7 @@ endif
 #
 # PyGreSQL
 #
-PYGRESQL_VERSION=5.1.2
+PYGRESQL_VERSION=b1e040e989b5b1b75f42c1103562bfe8f09f93c3
 PYGRESQL_DIR=PyGreSQL-$(PYGRESQL_VERSION)
 pygresql:
 	@echo "--- PyGreSQL"

ext @ 0979c356

-Subproject commit ae6b0c4bec82d9344b0e7c72ac0eb196ed431b14
+Subproject commit 0979c35672328ccdeaa0f8c3f2ac5c2d4aa4ce0f