Fix for issue #1639: make mock --scrub=all correctly back up successful builds from the chroot

Use `mv` instead of `cp` for backing up RPM builds. Moving saves time and disk space and preserves the original build timestamps.
Replaced the `util.run` call with `shutil.move`, following the suggestion from gemini-code-assist, then replaced `shutil.move` with `os.replace` to safely overwrite existing files.

Rename function backup_results to backup_build_results and replace self.backup with self.backup_on_clean for improved clarity and readability.

Author: sergiomb2

mock/py/mockbuild/backend.py

@@ -56,33 +56,15 @@ def __init__(self, config, uid_manager, plugins, state, buildroot, bootstrap_bui
         self.more_buildreqs = config['more_buildreqs']
         self.cache_alterations = config['cache_alterations']
 
-        self.backup = config['backup_on_clean']
-        self.backup_base_dir = config['backup_base_dir']
-
         # do we allow interactive root shells?
         self.no_root_shells = config['no_root_shells']
 
         self.private_network = not config['rpmbuild_networking']
         self.rpmbuild_noclean_option = None
 
-    @traceLog()
-    def backup_results(self):
-        srcdir = os.path.join(self.buildroot.basedir, "result")
-        if not os.path.exists(srcdir):
-            return
-        dstdir = os.path.join(self.backup_base_dir, self.config['root'])
-        file_util.mkdirIfAbsent(dstdir)
-        rpms = glob.glob(os.path.join(srcdir, "*rpm"))
-        if len(rpms) == 0:
-            return
-        self.state.state_log.info("backup_results: saving with cp %s %s", " ".join(rpms), dstdir)
-        util.run(cmd="cp %s %s" % (" ".join(rpms), dstdir))
-
     @traceLog()
     def clean(self):
         """clean out chroot with extreme prejudice :)"""
-        if self.backup:
-            self.backup_results()
         self.state.start("clean chroot")
         self.buildroot.delete()
         self.state.finish("clean chroot")

mock/py/mockbuild/buildroot.py

@@ -99,6 +99,8 @@ def __init__(self, config, uid_manager, state, plugins, bootstrap_buildroot=None
         self._lock_file = None
         self.selinux = (not self.config['plugin_conf']['selinux_enable']
                         and util.selinuxEnabled())
+        self.backup_on_clean = config['backup_on_clean']
+        self.backup_base_dir = config['backup_base_dir']
 
         self.chrootuid = config['chrootuid']
         self.chrootuser = config['chrootuser']
@@ -1046,12 +1048,36 @@ def wrap_host_file(self, filename):
 
         return util.BindMountedFile(chroot_filename, host_filename)
 
+    @traceLog()
+    def backup_build_results(self):
+        """
+        Back up the built RPMs before deleting the chroot and results, if the `backup_on_clean` option is enabled.
+        """
+        if self.backup_on_clean:
+            srcdir = os.path.join(self.basedir, "result")
+            if not os.path.exists(srcdir):
+                return
+            dstdir = os.path.join(self.config['backup_base_dir'], self.config['root'])
+            file_util.mkdirIfAbsent(dstdir)
+            rpms = glob.glob(os.path.join(srcdir, "*rpm"))
+            if len(rpms) == 0:
+                return
+            self.state.state_log.info("backup_build_results: saving with mv %s %s", " ".join(rpms), dstdir)
+            for rpm in rpms:
+                dest_path = os.path.join(dstdir, os.path.basename(rpm))
+                try:
+                    os.replace(rpm, dest_path)
+                except OSError as e:
+                    self.state.state_log.error("backup_build_results: error moving %s to %s: %s",
+                            rpm, dest_path, e)
+
     @traceLog()
     def delete(self):
         """
         Deletes the buildroot contents.
         """
         if os.path.exists(self.basedir):
+            self.backup_build_results()
             p = self.make_chroot_path()
             self._lock_buildroot(exclusive=True)
             util.orphansKill(p)

releng/release-notes-next/back_up_on_scrub.bugfix

@@ -0,0 +1,5 @@
+`mock --scrub=all` now correctly backs up successful builds from the buildroot. Fixes issue #1639.
+The backup process now uses `mv` semantics instead of `cp`, avoiding file duplication, preserving timestamps, and improving performance.
+Replaced the `util.run` call with `shutil.move`, following the suggestion from gemini-code-assist and providing a more idiomatic and portable Python implementation.
+Fix gemini-code-assist suggestion: `shutil.move` may raise "Error: Destination path already exists"; use `os.replace` to safely overwrite.
+Rename function backup_results to backup_build_results and replace self.backup with self.backup_on_clean for improved clarity and readability.