Keep re-creating the root directory for each build

Fixes: fedora-copr/copr#2916
Closes: #1227

mock/py/mockbuild/buildroot.py

@@ -211,7 +211,6 @@ def _setup_basedir(self):
         mockgid = grp.getgrnam('mock').gr_gid
         os.chown(self.basedir, os.getuid(), mockgid)
         os.chmod(self.basedir, 0o775)
-        file_util.mkdirIfAbsent(self.make_chroot_path())
 
     @traceLog()
     def _setup_result_dir(self):
@@ -276,6 +275,7 @@ def _fallback(message):
     def _init(self, prebuild):
         self.state.start("chroot init")
         self._setup_basedir()
+        file_util.mkdirIfAbsent(self.make_chroot_path())
         self.plugins.call_hooks('mount_root')
         # intentionally we do not call bootstrap hook here - it does not have sense
         self._setup_nosync()

releng/generate-release-notes

@@ -10,6 +10,7 @@ TRANSFORM = {
     "issue": "https://github.com/rpm-software-management/mock/issues/{id}",
     "PR": "https://github.com/rpm-software-management/mock/pull/{id}",
     "commit": "https://github.com/rpm-software-management/mock/commit/{id}",
+    "copr_issue": "https://github.com/fedora-copr/copr/issues/{id}",
 }
 
 TEMP_FILE = ".Release-Notes-Next.md"

releng/release-notes-next/create-rootdir-for-each-build.bugfix

@@ -0,0 +1,16 @@
+The [commit#1e13b56ce3c0efdf81][] caused that not only basedir was
+created just once per one Mock command, but that also rootdir was.
+Since Mock automatically unmounts rootdir **after each build** and then
+also **removes the rootdir** directory to finish the cleanup tasks (at
+least if tmpfs or other "root" plugin is in use, --resultdir is in
+use, ...), subsequent builds failed to re-mount the rootdir with, e.g.:
+
+    ERROR: Command failed:
+    $ mount -n -t tmpfs -o mode=0755 -o nr_inodes=0 -o size=140g mock_chroot_tmpfs /var/lib/mock/fedora-37-x86_64-1694797505.326095/root
+
+This caused problems e.g. [in Fedora Copr][copr_issue#2916] where each
+Mock build is actually a two-step build done like:
+
+    mock --spec foo.spec --sources . --resultdir ...
+
+So Mock first builds SRPM, and then builds RPMs (two builds in one run).