revert: display full subrepo output with --dry-run

Since the point of --dry-run is to show what will happen, the output with and
without it should agree.  And since revert wasn't being called on subrepos with
--dry-run before, revert in the subrepo had to be defanged in this case.

mercurial/cmdutil.py

@@ -2783,14 +2783,14 b' def revert(ui, repo, ctx, parents, *pats'
 
             _performrevert(repo, parents, ctx, actions)
 
-            # get the list of subrepos that must be reverted
-            subrepomatch = scmutil.match(ctx, pats, opts)
-            targetsubs = sorted(s for s in ctx.substate if subrepomatch(s))
-
-            if targetsubs:
-                # Revert the subrepos on the revert list
-                for sub in targetsubs:
-                    ctx.sub(sub).revert(ctx.substate[sub], *pats, **opts)
+        # get the list of subrepos that must be reverted
+        subrepomatch = scmutil.match(ctx, pats, opts)
+        targetsubs = sorted(s for s in ctx.substate if subrepomatch(s))
+
+        if targetsubs:
+            # Revert the subrepos on the revert list
+            for sub in targetsubs:
+                ctx.sub(sub).revert(ctx.substate[sub], *pats, **opts)
     finally:
         wlock.release()
 

mercurial/subrepo.py

@@ -884,7 +884,8 b' class hgsubrepo(abstractsubrepo):'
             self.filerevert(*pats, **opts)
 
         # Update the repo to the revision specified in the given substate
-        self.get(substate, overwrite=True)
+        if not opts.get('dry_run'):
+            self.get(substate, overwrite=True)
 
     def filerevert(self, *pats, **opts):
         ctx = self._repo[opts['rev']]
@@ -1693,7 +1694,8 b' class gitsubrepo(abstractsubrepo):'
                 util.rename(os.path.join(self._abspath, name),
                             os.path.join(self._abspath, bakname))
 
-        self.get(substate, overwrite=True)
+        if not opts.get('dry_run'):
+            self.get(substate, overwrite=True)
         return []
 
     def shortid(self, revid):

tests/test-subrepo.t

@@ -50,9 +50,16 b' test handling .hgsubstate "added" explic'
 Revert subrepo and test subrepo fileset keyword:
 
   $ echo b > s/a
+  $ hg revert --dry-run "set:subrepo('glob:s*')"
+  reverting subrepo s
+  reverting s/a (glob)
+  $ cat s/a
+  b
   $ hg revert "set:subrepo('glob:s*')"
   reverting subrepo s
   reverting s/a (glob)
+  $ cat s/a
+  a
   $ rm s/a.orig
 
 Revert subrepo with no backup. The "reverting s/a" line is gone since