tests: make a multi-statement hook in bundle2-exchange Windows compatible

This is similar to the fix in 7dd1870120b2.

tests/test-bundle2-exchange.t

@@ -7,6 +7,11 b' Test exchange of common information usin'
 
 enable obsolescence
 
+  $ cat > $TESTDIR/bundle2-pushkey-hook.sh << EOF
+  > echo pushkey: lock state after \"\$HG_NAMESPACE\"
+  > hg debuglock
+  > EOF
+
   $ cat >> $HGRCPATH << EOF
   > [experimental]
   > evolution=createmarkers,exchange
@@ -24,7 +29,7 b' enable obsolescence'
   > b2x-pretransactionclose.tip = hg log -r tip -T "pre-close-tip:{node|short} {phase} {bookmarks}\n"
   > b2x-transactionclose.tip = hg log -r tip -T "postclose-tip:{node|short} {phase} {bookmarks}\n"
   > b2x-transactionclose.env = sh -c  "HG_LOCAL= python \"$TESTDIR/printenv.py\" b2x-transactionclose"
-  > pushkey= echo pushkey: lock state after \"\$HG_NAMESPACE\"; hg debuglock
+  > pushkey= sh "$TESTDIR/bundle2-pushkey-hook.sh"
   > EOF
 
 The extension requires a repo (currently unused)