test-revert: add methodical revert with explicit file path

We now also test reverting file to the working directory parent
content. However this differs from the previously introduced test by using
the explicit path of each "case file" when calling revert. This should
result in the same result regarding file content and backup creation,
but the output of the `hg revert` call should differ.

tests/test-revert.t

@@ -595,3 +595,31 b' additional `.orig` backup file when appl'
   $ cd ..
   $ diff -U 0 -- content-base.txt content-base-all.txt | grep _
   [1]
+
+Test revert to parent content with explicit file name
+-----------------------------------------------------
+
+(setup from reference repo)
+
+  $ cp -r revert-ref revert-parent-explicit
+  $ cd revert-parent-explicit
+
+revert all files individually and check the output
+(output is expected to be different than in the --all case)
+
+  $ for file in `python ../gen-revert-cases.py filelist`; do
+  >   echo '### revert for:' $file;
+  >   hg revert $file;
+  >   echo
+  > done
+  ### revert for: modified_clean
+  no changes needed to modified_clean
+  
+
+check resulting directory againt the --all run
+(There should be no difference)
+
+  $ python ../dircontent.py > ../content-parent-explicit.txt
+  $ cd ..
+  $ diff -U 0 -- content-parent-all.txt content-parent-explicit.txt | grep _
+  [1]