unstable: do not consider internal phases when computing unstable

The revisions that are not part of the "working" set by other means should not
be considered for the evolution related computation.

This impact the test introduced in 5f9af8422b31 as this is actually a more
semantic fix of the issue.

mercurial/obsolete.py

@@ -939,7 +939,7 b' def clearobscaches(repo):'
 
 def _mutablerevs(repo):
     """the set of mutable revision in the repository"""
-    return repo._phasecache.getrevset(repo, phases.mutablephases)
+    return repo._phasecache.getrevset(repo, phases.relevant_mutable_phases)
 
 
 @cachefor(b'obsolete')

mercurial/phases.py

@@ -165,6 +165,7 b' phasenumber2.update({phase: phase for ph'
 phasenumber2.update({b'%i' % phase: phase for phase in phasenames})
 # record phase property
 mutablephases = (draft, secret, archived, internal)
+relevant_mutable_phases = (draft, secret)  # could be obsolete or unstable
 remotehiddenphases = (secret, archived, internal)
 localhiddenphases = (internal, archived)
 

tests/test-phases.t

@@ -1001,18 +1001,20 b' Commit is hidden as expected'
      summary:     A
   
 The hidden commit is an orphan but doesn't show up without --hidden
+And internal changesets are not considered for unstability.
 
   $ hg debugobsolete `hg id --debug -ir 0`
   1 new obsolescence markers
   obsoleted 1 changesets
-  $ hg --hidden log -G -r 'unstable()'
-  *  changeset:   1:c01c42dffc7f
+  $ hg --hidden log -G -r '(0::) - 0'
+  o  changeset:   1:c01c42dffc7f
   |  tag:         tip
   ~  user:        test
      date:        Thu Jan 01 00:00:00 1970 +0000
-     instability: orphan
      summary:     my test internal commit
   
+  $ hg --hidden log -G -r 'unstable()'
+
   $ hg log -G -r 'unstable()'