histedit-test: rename histedit-revspec into histedit-argument

We have no testing for argument. This small file seems perfect once but needs a
rename.

tests/test-histedit-arguments.t

@@ -0,0 +1,70 b''
+Test argument handling and various data parsing
+==================================================
+
+
+Enable extensions used by this test.
+  $ cat >>$HGRCPATH <<EOF
+  > [extensions]
+  > histedit=
+  > EOF
+
+Repo setup.
+  $ hg init foo
+  $ cd foo
+  $ echo alpha >> alpha
+  $ hg addr
+  adding alpha
+  $ hg ci -m one
+  $ echo alpha >> alpha
+  $ hg ci -m two
+  $ echo alpha >> alpha
+  $ hg ci -m three
+  $ echo alpha >> alpha
+  $ hg ci -m four
+  $ echo alpha >> alpha
+  $ hg ci -m five
+
+  $ hg log --style compact --graph
+  @  4[tip]   08d98a8350f3   1970-01-01 00:00 +0000   test
+  |    five
+  |
+  o  3   c8e68270e35a   1970-01-01 00:00 +0000   test
+  |    four
+  |
+  o  2   eb57da33312f   1970-01-01 00:00 +0000   test
+  |    three
+  |
+  o  1   579e40513370   1970-01-01 00:00 +0000   test
+  |    two
+  |
+  o  0   6058cbb6cfd7   1970-01-01 00:00 +0000   test
+       one
+  
+
+Run a dummy edit to make sure we get tip^^ correctly via revsingle.
+--------------------------------------------------------------------
+
+  $ HGEDITOR=cat hg histedit "tip^^"
+  pick eb57da33312f 2 three
+  pick c8e68270e35a 3 four
+  pick 08d98a8350f3 4 five
+  
+  # Edit history between eb57da33312f and 08d98a8350f3
+  #
+  # Commands:
+  #  p, pick = use commit
+  #  e, edit = use commit, but stop for amending
+  #  f, fold = use commit, but fold into previous commit (combines N and N-1)
+  #  d, drop = remove commit from history
+  #  m, mess = edit message without changing commit content
+  #
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+
+Run on a revision not ancestors of the current working directory.
+--------------------------------------------------------------------
+
+  $ hg up 2
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg histedit -r 4
+  abort: 08d98a8350f3 is not an ancestor of working directory
+  [255]