graphlog: fix --follow FILE and relative paths

The situation is complicated because filelog() revset uses a match object in
relpath mode while follow() revset interprets the filename as a manifest entry.

hgext/graphlog.py

@@ -353,7 +353,9 b' def _makelogrevset(repo, pats, opts, rev'
             fnopats = (('_ancestors', '_fancestors'),
                        ('_descendants', '_fdescendants'))
             if pats:
-                opts[fpats[followfirst]] = list(pats)
+                # follow() revset inteprets its file argument as a
+                # manifest entry, so use match.files(), not pats.
+                opts[fpats[followfirst]] = list(match.files())
             else:
                 opts[fnopats[followdescendants][followfirst]] = str(startrev)
         else:

tests/test-glog.t

@@ -2026,6 +2026,20 b' Test subdir'
           ('string', 'r:')
           ('string', 'd:relpath'))
         ('string', 'p:.'))))
+  $ testlog ../b
+  []
+  (group
+    (group
+      (func
+        ('symbol', 'filelog')
+        ('string', '../b'))))
+  $ testlog -f ../b
+  []
+  (group
+    (group
+      (func
+        ('symbol', 'follow')
+        ('string', 'b'))))
   $ cd ..
 
 Test --hidden