buildhistory: Restoring files from preserve list

This fix will ensure that, when we activate feature
`BUILDHISTORY_RESET`, files marked to keep on feature
`BUILDHISTORY_PRESERVE` will indeed exist is buildhistory
final path since they are moved to buildhistory/old but
not restored at any point.

(From OE-Core rev: 8160fd3c042283a47a2601e1797847c303e1e7e5)

Signed-off-by: Pedro Ferreira <Pedro.Silva.Ferreira@criticaltechworks.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 9f68a45aa238ae5fcdfaca71ba0e7015e9cb720e)
Signed-off-by: Steve Sakoman <steve@sakoman.com>

meta/classes/buildhistory.bbclass

@@ -108,6 +108,7 @@ python buildhistory_emit_pkghistory() {
     import json
     import shlex
     import errno
+    import shutil
 
     pkghistdir = d.getVar('BUILDHISTORY_DIR_PACKAGE')
     oldpkghistdir = d.getVar('BUILDHISTORY_OLD_DIR_PACKAGE')
@@ -221,6 +222,20 @@ python buildhistory_emit_pkghistory() {
         items.sort()
         return ' '.join(items)
 
+    def preservebuildhistoryfiles(pkg, preserve):
+        if os.path.exists(os.path.join(oldpkghistdir, pkg)):
+            listofobjs = os.listdir(os.path.join(oldpkghistdir, pkg))
+            for obj in listofobjs:
+                if obj not in preserve:
+                    continue
+                try:
+                    bb.utils.mkdirhier(os.path.join(pkghistdir, pkg))
+                    shutil.copyfile(os.path.join(oldpkghistdir, pkg, obj), os.path.join(pkghistdir, pkg, obj))
+                except IOError as e:
+                    bb.note("Unable to copy file. %s" % e)
+                except EnvironmentError as e:
+                    bb.note("Unable to copy file. %s" % e)
+
     pn = d.getVar('PN')
     pe = d.getVar('PE') or "0"
     pv = d.getVar('PV')
@@ -248,6 +263,14 @@ python buildhistory_emit_pkghistory() {
     if not os.path.exists(pkghistdir):
         bb.utils.mkdirhier(pkghistdir)
     else:
+        # We need to make sure that all files kept in
+        # buildhistory/old are restored successfully
+        # otherwise next block of code wont have files to
+        # check and purge
+        if d.getVar("BUILDHISTORY_RESET"):
+            for pkg in packagelist:
+                preservebuildhistoryfiles(pkg, preserve)
+
         # Remove files for packages that no longer exist
         for item in os.listdir(pkghistdir):
             if item not in preserve: