trying to fix the reverting paragraph

if you dissagree, dont hesitate to revert this commit or flame, but at least we should not claim that svn cannot revert commits except by recommiting the old version


git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@19388 b3059339-0415-0410-9bf9-f77b7e298cf2

DOCS/tech/svn-howto.txt

@@ -151,11 +151,42 @@ I. BASICS:
 
 9. Reverting broken commits
 
-  There is no Subversion equivalent of the 'cvs admin -o' command. Instead,
-  be very careful about what you commit! If somehow you broke something,
-  revert the changes locally and re-commit with a proper commit message.
-  You may want to use 'svn cat -r<revision> <filename>' to inspect an older
-  revision.
+  There are 2 ways to reverse a change, they differ significantly in what they
+  do to the svn repository
+  The recommit old method:
+    svn merge
+    svn ci <file>
+    This simply changes the file(s) back to their old version localy and then
+    the change is commited as if it is a new change
+  The svn copy method
+    svn rm <file>
+    svn ci <file>
+    svn cp -r<good revision> svn://svn.mplayerhq.hu/mplayer/trunk/[<path>/]<file> <file>
+    svn ci <file>
+    This simply removes the file and then copies the last good version with
+    its history over it, this method can only be used to revert the n last
+    commits but not to revert a bad commit in the middle of its history
+  Neither method will change the history, checking out an old version will
+  always return exactly that revision with all its bugs and features. The
+  difference is that with the svn copy method the broken commit will not be
+  part of the directly vissible history of the revisions after the reversal
+  So if the change was completly broken like reindenting a file against the
+  maintainers decission, or a change which mixed functional and cosmetic
+  changes then its better if its not part of the vissible history as it
+  would make it hard to read, review and would also break svn annotate
+  For the example of a change which mixed functional and cosmetic parts they
+  should of course be commited again after the reversal but seperatly, so one
+  change with the functional stuff and one with the cosmetics
+  OTOH if the change which you want to reverse was simply buggy but not
+  totally broken then it should be reversed with svn merge as otherwise
+  the fact that the change was bad would be hidden
+  One method to decide which reversal method is best is to ask yourself
+  if theres any value in seeing the whole bad change and its removial
+  in svn vs. just seeing a comment that says what has been reversed while
+  the actual change does not clutter the immedeatly vissible history and
+  svn annotate.
+  If you are even just slightly uncertain how to revert something then ask on
+  the mplayer-dev mailinglist.
 
 
 10. Reverting local changes