reproin: Don't hardcode HEAD~10 in afterlife solution

Using HEAD~10 is fragile.  It needs to be updated if any of the steps
above are modified, and it assumes the solutions above were achieved
in exactly the same way, but it would be possible to get to the same
state with a different number of commits (e.g., by using 'datalad
download-url --path code/').

_episodes/03-01-reproin.md

@@ -470,12 +470,14 @@ And because this record is complete, we can now simply throw away the input BIDS
 
 > ## Task: Verify that the BIDS subdataset is unmodified and uninstall it
 >
-> Use the [datalad diff] command to check for modifications of the subdataset,
-> and the [datalad uninstall] to delete it.
+> Use the [datalad diff] command and `git log` to verify that the subdataset is
+> in the same state as when it was initially added.  Then use [datalad
+> uninstall] to delete it.
 >
 > > ## Solution
 > > ~~~
-> > % datalad diff --revision HEAD~10 -- inputs
+> > % datalad diff -- inputs
+> > % git log -- inputs
 > > % datalad uninstall --dataset . inputs --recursive
 > > ~~~
 > > {: .bash}