test-revert: add methodical revert to "base" with explicit file path

We now also test reverting file to another revision's content. However
this differs from 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

@@ -623,3 +623,30 b' check resulting directory againt the --a'
   $ cd ..
   $ diff -U 0 -- content-parent-all.txt content-parent-explicit.txt | grep _
   [1]
+
+Test revert to "base" content with explicit file name
+-----------------------------------------------------
+
+(setup from reference repo)
+
+  $ cp -r revert-ref revert-base-explicit
+  $ cd revert-base-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 --rev 'desc(base)';
+  >   echo
+  > done
+  ### revert for: modified_clean
+  
+
+check resulting directory againt the --all run
+(There should be no difference)
+
+  $ python ../dircontent.py > ../content-base-explicit.txt
+  $ cd ..
+  $ diff -U 0 -- content-base-all.txt content-base-explicit.txt | grep _
+  [1]