--- a/mercurial/commands.py	Thu May 03 12:10:47 2018 +0900
+++ b/mercurial/commands.py	Thu May 03 12:04:36 2018 +0900
@@ -359,11 +359,12 @@
     else:
         def makefunc(get, fmt):
             return get
+    datahint = rootfm.datahint()
     funcmap = [(makefunc(get, fmt), sep) for fn, sep, get, fmt in opmap
-               if opts.get(opnamemap.get(fn, fn))]
+               if opts.get(opnamemap.get(fn, fn)) or fn in datahint]
     funcmap[0] = (funcmap[0][0], '') # no separator in front of first column
     fields = ' '.join(fn for fn, sep, get, fmt in opmap
-                      if opts.get(opnamemap.get(fn, fn)))
+                      if opts.get(opnamemap.get(fn, fn)) or fn in datahint)
 
     def bad(x, y):
         raise error.Abort("%s: %s" % (x, y))

--- a/tests/test-annotate.t	Thu May 03 12:10:47 2018 +0900
+++ b/tests/test-annotate.t	Thu May 03 12:04:36 2018 +0900
@@ -76,6 +76,11 @@
   $ hg annotate -T'{lines % "{rev} {node|shortest}: {line}"}' a
   0 8435: a
 
+'{line_number}' field should be populated as necessary
+
+  $ hg annotate -T'{lines % "{rev}:{line_number}: {line}"}' a
+  0:1: a
+
   $ cat <<EOF >>a
   > a
   > a