Add a hint for revert --all when aborting

mercurial/commands.py

@@ -2291,7 +2291,8 b' def revert(ui, repo, *pats, **opts):'
     """
 
     if not pats and not opts['all']:
-        raise util.Abort(_('no files or directories specified'))
+        raise util.Abort(_('no files or directories specified; '
+                           'use --all to revert the whole repo'))
 
     parent, p2 = repo.dirstate.parents()
     if opts['rev']:

tests/test-revert.out

@@ -55,7 +55,7 b' executable'
 adding a
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 % should fail - no arguments
-abort: no files or directories specified
+abort: no files or directories specified; use --all to revert the whole repo
 % should succeed
 reverting a
 %% issue332