[PATCH 1 of 2 evolve-ext] evolve: remove meaningless transaction nesting

[FUJIWARA Katsunori]

# HG changeset patch
# User FUJIWARA Katsunori <foozy at lares.dti.ne.jp>
# Date 1453497481 -32400
#      Sat Jan 23 06:18:01 2016 +0900
# Node ID d5ac28ad9f41585be4bc35466910f2733267c332
# Parent  983f2e4dbe5d4d97d6ca82f6679913d75c1f2577
# Available At https://foozy@bitbucket.org/foozy/hgext-evolve
#              hg pull https://foozy@bitbucket.org/foozy/hgext-evolve -r d5ac28ad9f41
evolve: remove meaningless transaction nesting

Before this patch, functions below nest transaction scope, even though
they are invoked only inside a transaction scope created at _solveone().

  - _solvebumped()
  - _solvedivergent()
  - relocate() via _solveunstable() or _solvebumped()

Transaction nesting is useful for localizing "success" (e.g. one scope
per commit inside wider scope for multiple committing).

But such nesting is redundant for _solveone(), because there is no
code path, which causes failure after successfully closing inner
transaction(s).

In addition to it, this nesting makes it complicated to close current
transaction successfully with exception raising inside inner scope,
like "hg shelve" at detection of conflicts. "tr.close()" is required
at each outer scopes for such case.

To remove meaningless transaction nesting, this patch replaces
repo.transaction() in functions above by repo.currenttransaction().
This reuses transaction created at _solveone().

This patch also adds 'assert tr' after getting current running
transaction, to avoid invocation of functions above without
transaction.

diff --git a/hgext/evolve.py b/hgext/evolve.py
--- a/hgext/evolve.py
+++ b/hgext/evolve.py
@@ -946,7 +946,8 @@ def relocate(repo, orig, dest, pctx=None
             repo.ui.note(_('The stale commit message reference to %s could '
                            'not be updated\n') % sha1)
 
-    tr = repo.transaction('relocate')
+    tr = repo.currenttransaction()
+    assert tr
     try:
         try:
             if repo['.'].rev() != dest.rev():
@@ -986,9 +987,8 @@ def relocate(repo, orig, dest, pctx=None
             raise
         oldbookmarks = repo.nodebookmarks(nodesrc)
         _finalizerelocate(repo, orig, dest, nodenew, tr)
-        tr.close()
     finally:
-        tr.release()
+        pass # TODO: remove this redundant try/finally block
     return nodenew
 
 def _bookmarksupdater(repo, oldid, tr):
@@ -1858,7 +1858,8 @@ def _solvebumped(ui, repo, bumped, dryru
     newid = tmpctx = None
     tmpctx = bumped
     # Basic check for common parent. Far too complicated and fragile
-    tr = repo.transaction('bumped-stabilize')
+    tr = repo.currenttransaction()
+    assert tr
     bmupdate = _bookmarksupdater(repo, bumped.node(), tr)
     try:
         if not list(repo.set('parents(%d) and parents(%d)', bumped, prec)):
@@ -1924,10 +1925,9 @@ def _solvebumped(ui, repo, bumped, dryru
             obsolete.createmarkers(repo, [(tmpctx, (repo[newid],))],
                                    flag=obsolete.bumpedfix)
         bmupdate(newid)
-        tr.close()
         repo.ui.status(_('committed as %s\n') % node.short(newid))
     finally:
-        tr.release()
+        pass # TODO: remove this redundant try/finally block
     # reroute the working copy parent to the new changeset
     repo.dirstate.beginparentchange()
     repo.dirstate.setparents(newid, node.nullid)
@@ -2036,7 +2036,8 @@ def _solvedivergent(ui, repo, divergent,
 """)
     if progresscb: progresscb()
     emtpycommitallowed = repo.ui.backupconfig('ui', 'allowemptycommit')
-    tr = repo.transaction('stabilize-divergent')
+    tr = repo.currenttransaction()
+    assert tr
     try:
         repo.ui.setconfig('ui', 'allowemptycommit', True)
         repo.dirstate.beginparentchange()
@@ -2051,10 +2052,8 @@ def _solvedivergent(ui, repo, divergent,
             new = repo['.']
         obsolete.createmarkers(repo, [(other, (new,))])
         phases.retractboundary(repo, tr, other.phase(), [new.node()])
-        tr.close()
     finally:
         repo.ui.restoreconfig(emtpycommitallowed)
-        tr.release()
 
 def divergentdata(ctx):
     """return base, other part of a conflict