Set Gerrit to 2.16.26

Change-Id: If084acc819d1d92c9f63fd3ae9c780e3a2c6f8e1

centos/7/Dockerfile

diff --git a/centos/7/Dockerfile b/centos/7/Dockerfile
index 3581ca0..0595959 100644
--- a/centos/7/Dockerfile
+++ b/centos/7/Dockerfile
@@ -8,7 +8,7 @@
 # (pre-trans Gerrit script needs to have access to the Java command)
 RUN yum -y install initscripts && \
     yum -y install java-1.8.0-openjdk && \
-    yum -y install gerrit-2.16.25-1 && rm -Rf /var/gerrit/{logs,tmp}/* && rm -Rf /var/gerrit/.gerritcodereview && \
+    yum -y install gerrit-2.16.26-1 && rm -Rf /var/gerrit/{logs,tmp}/* && rm -Rf /var/gerrit/.gerritcodereview && \
     yum -y clean all
 
 USER gerrit

ubuntu/16/Dockerfile

diff --git a/ubuntu/16/Dockerfile b/ubuntu/16/Dockerfile
index 66c8b2a..2ed10f8 100644
--- a/ubuntu/16/Dockerfile
+++ b/ubuntu/16/Dockerfile
@@ -12,7 +12,7 @@
 # Install OpenJDK and Gerrit in two subsequent transactions
 # (pre-trans Gerrit script needs to have access to the Java command)
 RUN apt-get -y install openjdk-8-jdk
-RUN apt-get -y install gerrit=2.16.25-1 && apt-mark hold gerrit && rm -f /var/gerrit/logs/*
+RUN apt-get -y install gerrit=2.16.26-1 && apt-mark hold gerrit && rm -f /var/gerrit/logs/*
 
 USER gerrit
 RUN java -jar /var/gerrit/bin/gerrit.war init --batch --install-all-plugins -d /var/gerrit