bookmarks: accept explicit -r 'wdir()' when adding new bookmarks (issue6218)

Even though the bookmark semantics can't be fully encoded to the virtual
working changeset idea, the active bookmark can be considered a bookmark
of the working revision.

Before, 'tgt' was None, and changes=[(bm, None)] means deleting a bookmark
named 'bm'.

mercurial/bookmarks.py

@@ -958,8 +958,13 b' def addbookmarks(repo, tr, names, rev=No'
     if rev:
         repo = scmutil.unhidehashlikerevs(repo, [rev], b'nowarn')
 
-    ctx = scmutil.revsingle(repo, rev)
+    ctx = scmutil.revsingle(repo, rev, None)
+    # bookmarking wdir means creating a bookmark on p1 and activating it
+    activatenew = not inactive and ctx.rev() is None
+    if ctx.node() is None:
+        ctx = ctx.p1()
     tgt = ctx.node()
+    assert tgt
 
     for mark in names:
         mark = checkformat(repo, mark)
@@ -984,7 +989,7 b' def addbookmarks(repo, tr, names, rev=No'
             repo.ui.warn(b"(%s)\n" % msg)
 
     marks.applychanges(repo, tr, changes)
-    if not inactive and cur == marks[newact] and not rev:
+    if activatenew and cur == marks[newact]:
         activate(repo, newact)
     elif cur != tgt and newact == repo._activebookmark:
         deactivate(repo)

tests/test-bookmarks.t

@@ -619,6 +619,16 b" deactivate current 'Z', but also add 'Y'"
      x  y                      2:db815d6d32e6
   $ hg bookmark Z
 
+bookmark wdir to activate it (issue6218)
+
+  $ hg bookmark -d Z
+  $ hg bookmark -r 'wdir()' Z
+  $ hg bookmark -l
+     X2                        1:925d80f479bb
+     Y                         2:db815d6d32e6
+   * Z                         2:db815d6d32e6
+     x  y                      2:db815d6d32e6
+
 test clone
 
   $ hg bookmark -r 2 -i @