histedit: handle multiple spaces between action and hash (issue3893)

There is some clue that the previous code intended to handle that but it was
actually not the case.

As a result action could apply to the empty string '' changeset,
leading to the use the current working directory parent in some
operations.

hgext/histedit.py

@@ -722,10 +722,7 b' def verifyrules(rules, repo, ctxs):'
         if ' ' not in r:
             raise util.Abort(_('malformed line "%s"') % r)
         action, rest = r.split(' ', 1)
-        if ' ' in rest.strip():
-            ha, rest = rest.split(' ', 1)
-        else:
-            ha = r.strip()
+        ha = rest.strip().split(' ', 1)[0]
         try:
             if repo[ha] not in ctxs:
                 raise util.Abort(

tests/test-histedit-arguments.t

@@ -68,3 +68,34 b' Run on a revision not ancestors of the c'
   $ hg histedit -r 4
   abort: 08d98a8350f3 is not an ancestor of working directory
   [255]
+  $ hg up --quiet
+
+Test short version of command
+---------------------------------------
+
+Note: we use varying amounts of white space between command name and changeset
+short hash. This tests issue3893.
+
+  $ HGEDITOR=cat hg histedit "tip^^" --commands - << EOF
+  > pick eb57da33312f 2 three
+  > p    c8e68270e35a 3 four
+  > f 08d98a8350f3 4 five
+  > EOF
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  reverting alpha
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  four
+  ***
+  five
+  
+  
+  
+  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
+  HG: Leave message empty to abort commit.
+  HG: --
+  HG: user: test
+  HG: branch 'default'
+  HG: changed alpha
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  saved backup bundle to $TESTTMP/foo/.hg/strip-backup/*-backup.hg (glob)