centos: do not use $releasever in .repo files

For centos stream, the $releasever is just the major version.  Several
of our .repo files are using $releasever in their path, and I think
that 8-stream installs are actually using 8 repos to install from.
For 9-stream, which doesn't have a corresponding 9, we're getting
errors enabling some of the aarch64 tests.

Replace all the $releasever expansions in the .repo files with the
exact version they are being installed for.  They don't need to be
generic; we are installing these specific repos for each DIB_RELEASE,
so they don't mix-and-match.

Change-Id: I48d438d8f51280cd060433fc8a67358d8345287f

diskimage_builder/elements/centos-minimal/yum.repos.d/8-stream/appstream.repo

@@ -1,5 +1,5 @@
 [Stream-AppStream]
 name=CentOS-Stream - AppStream
-mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=AppStream
+mirrorlist=http://mirrorlist.centos.org/?release=8-stream&arch=$basearch&repo=AppStream
 gpgcheck=0
 

diskimage_builder/elements/centos-minimal/yum.repos.d/8-stream/base.repo

@@ -1,5 +1,5 @@
 [Stream-BaseOS]
 name=CentOS-Stream - Base
-mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=BaseOS
+mirrorlist=http://mirrorlist.centos.org/?release=8-stream&arch=$basearch&repo=BaseOS
 gpgcheck=0
 

diskimage_builder/elements/yum-minimal/root.d/08-yum-chroot

@@ -140,10 +140,13 @@ function _install_repos {
     # ${TMPDIR}/yum-$USER-random.  Since we don't need this once the
     # initial download happens, redirect TMPDIR for this call so we
     # can clean it up nicely
+    #
+    # Note that the $releasever for centos-stream is just the major
+    # version.  There is another variable "$stream" that we don't pass
     local temp_tmp
     temp_tmp=$(mktemp -d)
     TMPDIR=${temp_tmp} ${HOST_YUM_DOWNLOADER} --verbose \
-        --releasever=${DIB_RELEASE} \
+        --releasever=${DIB_RELEASE/-*/} \
         --setopt=reposdir=$repo \
         --setopt=cachedir=$temp_tmp \
         --destdir=$WORKING \
@@ -205,8 +208,8 @@ function _install_pkg_manager {
     # the yumdownloader calls above in _install_repos want to use
     # ~/.rpmdb/ ... there is nothing in the build-system /var/lib/rpm!
     #
-    # Another issue we hit is having to set --releasedir here.  yum
+    # Another issue we hit is having to set --releasever here.  yum
-    # determines $releasevar based on (more or less) "rpm -q
+    # determines $releasever based on (more or less) "rpm -q
     # --whatprovides $distroverpkg".  By default, this is
     # "redhat-release" (fedora-release provides redhat-release) but
     # some platforms like CentOS override it in /etc/yum.conf (to

roles/dib-setup-gate-mirrors/templates/centos-minimal/8-stream/appstream.repo.j2

@@ -1,5 +1,5 @@
 [Stream-AppStream]
 name=CentOS-Stream - AppStream
-baseurl=https://{{ mirror_fqdn }}/centos/$releasever/AppStream/$basearch/os/
+baseurl=https://{{ mirror_fqdn }}/centos/8-stream/AppStream/$basearch/os/
 gpgcheck=0
 

roles/dib-setup-gate-mirrors/templates/centos-minimal/8-stream/base.repo.j2

@@ -1,5 +1,5 @@
 [Stream-BaseOS]
 name=CentOS-Stream - Base
-baseurl=https://{{ mirror_fqdn }}/centos/$releasever/BaseOS/$basearch/os/
+baseurl=https://{{ mirror_fqdn }}/centos/8-stream/BaseOS/$basearch/os/
 gpgcheck=0