rebase: prioritize indicating an interrupted rebase over update (issue5838)

This should also cover the transplant extension, and any other non clearable
states.

mercurial/cmdutil.py

@@ -3208,8 +3208,16 b' def checkunfinished(repo, commit=False):'
     if found. It's probably good to check this right before
     bailifchanged().
     '''
+    # Check for non-clearable states first, so things like rebase will take
+    # precedence over update.
     for f, clearable, allowcommit, msg, hint in unfinishedstates:
-        if commit and allowcommit:
+        if clearable or (commit and allowcommit):
+            continue
+        if repo.vfs.exists(f):
+            raise error.Abort(msg, hint=hint)
+
+    for f, clearable, allowcommit, msg, hint in unfinishedstates:
+        if not clearable or (commit and allowcommit):
             continue
         if repo.vfs.exists(f):
             raise error.Abort(msg, hint=hint)

tests/test-rebase-abort.t

@@ -387,10 +387,9 b' New operations are blocked with the corr'
   .hg/undo.dirstate
   .hg/updatestate
 
-XXX: This should complain about needing to abort/continue rebase
   $ hg rebase -s 3 -d tip
-  abort: last update was interrupted
-  (use 'hg update' to get a consistent checkout)
+  abort: rebase in progress
+  (use 'hg rebase --continue' or 'hg rebase --abort')
   [255]
   $ hg up .
   abort: rebase in progress
@@ -401,10 +400,9 b' XXX: This should complain about needing '
   (use 'hg rebase --continue' or 'hg rebase --abort')
   [255]
 
-XXX: This should complain about needing to abort/continue rebase
   $ hg graft 3
-  abort: last update was interrupted
-  (use 'hg update' to get a consistent checkout)
+  abort: rebase in progress
+  (use 'hg rebase --continue' or 'hg rebase --abort')
   [255]
 
   $ hg rebase --abort