revert: move targetsubs calculation down to its use

A future patch will be reorganizing this section of the code into two paths, and
targetsubs complicates this by existing in the middle of one path, but not the
other. We fix that by moving it 200 lines down, to the only place it's used.

mercurial/cmdutil.py

@@ -2503,9 +2503,6 b' def revert(ui, repo, ctx, parents, *pats'
             if abs not in names:
                 names[abs] = m.rel(abs), m.exact(abs)
 
-        # get the list of subrepos that must be reverted
-        targetsubs = sorted(s for s in ctx.substate if m(s))
-
         # Find status of all file in `names`.
         m = scmutil.matchfiles(repo, names)
 
@@ -2692,6 +2689,10 b' def revert(ui, repo, ctx, parents, *pats'
         if not opts.get('dry_run'):
             _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: