changelog: fix readpending if no pending data exist (issue4609)

Since transaction are used for more than just changesets, it is possible
to have a transaction without new changesets at all. In this case no
''00changelog.i.a' are written. In all cases the 'changelog.readpending'
method is called if the repository has any pending data. The 'revlog' logic
provides empty content if the file is missing, so the whole operation
resulted in an empty changelog.

We now skip reading the pending file if it is missing.

mercurial/changelog.py

@@ -267,6 +267,8 b' class changelog(revlog.revlog):'
         self.checkinlinesize(tr)
 
     def readpending(self, file):
+        if not self.opener.exists(file):
+            return # no pending data for changelog
         r = revlog.revlog(self.opener, file)
         self.index = r.index
         self.nodemap = r.nodemap

tests/test-bundle2-exchange.t

@@ -72,7 +72,7 b' Add more obsolescence information'
 clone --pull
 
   $ hg -R main phase --public cd010b8cd998
-  pre-close-tip:000000000000 public 
+  pre-close-tip:02de42196ebe draft 
   postclose-tip:02de42196ebe draft 
   txnclose hook: HG_PHASES_MOVED=1 HG_TXNID=TXN:* HG_TXNNAME=phase (glob)
   $ hg clone main other --pull --rev 9520eea781bc
@@ -98,7 +98,7 b' clone --pull'
 pull
 
   $ hg -R main phase --public 9520eea781bc
-  pre-close-tip:000000000000 public 
+  pre-close-tip:02de42196ebe draft 
   postclose-tip:02de42196ebe draft 
   txnclose hook: HG_PHASES_MOVED=1 HG_TXNID=TXN:* HG_TXNNAME=phase (glob)
   $ hg -R other pull -r 24b6387c8c8c
@@ -128,13 +128,13 b' pull'
 pull empty (with phase movement)
 
   $ hg -R main phase --public 24b6387c8c8c
-  pre-close-tip:000000000000 public 
+  pre-close-tip:02de42196ebe draft 
   postclose-tip:02de42196ebe draft 
   txnclose hook: HG_PHASES_MOVED=1 HG_TXNID=TXN:* HG_TXNNAME=phase (glob)
   $ hg -R other pull -r 24b6387c8c8c
   pulling from $TESTTMP/main (glob)
   no changes found
-  pre-close-tip:000000000000 public 
+  pre-close-tip:24b6387c8c8c public 
   postclose-tip:24b6387c8c8c public 
   txnclose hook: HG_NEW_OBSMARKERS=0 HG_PHASES_MOVED=1 HG_SOURCE=pull HG_TXNID=TXN:* HG_TXNNAME=pull (glob)
   file:/*/$TESTTMP/main HG_URL=file:$TESTTMP/main (glob)
@@ -204,7 +204,7 b' add extra data to test their exchange du'
   $ hg -R other bookmark --rev cd010b8cd998 book_32af
 
   $ hg -R main phase --public eea13746799a
-  pre-close-tip:000000000000 public 
+  pre-close-tip:02de42196ebe draft book_02de
   postclose-tip:02de42196ebe draft book_02de
   txnclose hook: HG_PHASES_MOVED=1 HG_TXNID=TXN:* HG_TXNNAME=phase (glob)
 
@@ -344,7 +344,7 b' push over http'
   $ cat other.pid >> $DAEMON_PIDS
 
   $ hg -R main phase --public 32af7686d403
-  pre-close-tip:000000000000 public 
+  pre-close-tip:02de42196ebe draft book_02de
   postclose-tip:02de42196ebe draft book_02de
   txnclose hook: HG_PHASES_MOVED=1 HG_TXNID=TXN:* HG_TXNNAME=phase (glob)
   $ hg -R main push http://localhost:$HGPORT2/ -r 32af7686d403 --bookmark book_32af

tests/test-pending.t

@@ -113,3 +113,27 b' test external hook'
   rollback completed
   abort: pretxnchangegroup hook exited with status 1
   pull 0000000000000000000000000000000000000000
+
+Test that pending on transaction without changegroup see the normal changegroup(
+(issue4609)
+
+  $ cat <<EOF > parent/.hg/hgrc
+  > [hooks]
+  > pretxnchangegroup=
+  > pretxnclose = hg tip -T 'tip: {node|short}\n'
+  > [phases]
+  > publishing=False
+  > EOF
+
+setup
+
+  $ cd parent
+  $ echo a > a
+  $ hg add a
+  $ hg commit -m a
+  tip: cb9a9f314b8b
+
+actual test
+
+  $ hg phase --public .
+  tip: cb9a9f314b8b