Rpm: replace hyphens from version.

Reviewed at https://reviews.apache.org/r/37806/
diff --git a/builder/deb/ubuntu-trusty/build.sh b/builder/deb/ubuntu-trusty/build.sh
index 87c2bc0..bb2b799 100755
--- a/builder/deb/ubuntu-trusty/build.sh
+++ b/builder/deb/ubuntu-trusty/build.sh
@@ -25,9 +25,6 @@
 export DEBFULLNAME='Apache Aurora'
 export DEBEMAIL='dev@aurora.apache.org'
 
-# Replace underscores in version ID.
-export AURORA_VERSION=$(echo $AURORA_VERSION | tr '_' '-')
-
 dch \
   --newversion $AURORA_VERSION \
   --package apache-aurora \
diff --git a/builder/rpm/centos-7/build.sh b/builder/rpm/centos-7/build.sh
index 9e8eae9..912f7c7 100755
--- a/builder/rpm/centos-7/build.sh
+++ b/builder/rpm/centos-7/build.sh
@@ -23,6 +23,9 @@
 cp -R /specs/rpm .
 cd rpm
 
+# Replace hyphens in version ID.
+export AURORA_VERSION=$(echo $AURORA_VERSION | tr '-' '_')
+
 make srpm
 yum-builddep -y ../../../dist/rpmbuild/SRPMS/*
 make rpm