graphmod: fix seen state handling for > 2 parents (issue5174)

When there are more than 2 parents for a given node (in a sparse graph), extra
dummy nodes are inserted to transition the lines more gradually. However, since
the seen state was not updated when yielding the extra nodes, the wrong graph
styles were being applied to the nodes.

mercurial/graphmod.py

@@ -401,6 +401,7 b' def asciiedges(type, char, lines, state,'
     edges = [(nodeidx, nextseen.index(p))
              for p in knownparents if p != nullrev]
 
+    seen[:] = nextseen
     while len(newparents) > 2:
         # ascii() only knows how to add or remove a single column between two
         # calls. Nodes with more than two parents break this constraint so we
@@ -422,7 +423,6 b' def asciiedges(type, char, lines, state,'
     if len(newparents) > 1:
         edges.append((nodeidx, nodeidx + 1))
     nmorecols = len(nextseen) - ncols
-    seen[:] = nextseen
     # remove current node from edge characters, no longer needed
     state['edges'].pop(rev, None)
     yield (type, char, lines, (nodeidx, edges, ncols, nmorecols))

tests/test-glog.t

@@ -2736,3 +2736,58 b' behavior with newlines'
   
   
   $ cd ..
+
+When inserting extra line nodes to handle more than 2 parents, ensure that
+the right node styles are used (issue5174):
+
+  $ hg init repo-issue5174
+  $ cd repo-issue5174
+  $ echo a > f0
+  $ hg ci -Aqm 0
+  $ echo a > f1
+  $ hg ci -Aqm 1
+  $ echo a > f2
+  $ hg ci -Aqm 2
+  $ hg co ".^"
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ echo a > f3
+  $ hg ci -Aqm 3
+  $ hg co ".^^"
+  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
+  $ echo a > f4
+  $ hg ci -Aqm 4
+  $ hg merge -r 2
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -qm 5
+  $ hg merge -r 3
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  $ hg ci -qm 6
+  $ hg log -G -r '0 | 1 | 2 | 6'
+  @    changeset:   6:851fe89689ad
+  :\   tag:         tip
+  : :  parent:      5:4f1e3cf15f5d
+  : :  parent:      3:b74ba7084d2d
+  : :  user:        test
+  : :  date:        Thu Jan 01 00:00:00 1970 +0000
+  : :  summary:     6
+  : :
+  : \
+  : :\
+  : o :  changeset:   2:3e6599df4cce
+  : :/   user:        test
+  : :    date:        Thu Jan 01 00:00:00 1970 +0000
+  : :    summary:     2
+  : :
+  : o  changeset:   1:bd9a55143933
+  :/   user:        test
+  :    date:        Thu Jan 01 00:00:00 1970 +0000
+  :    summary:     1
+  :
+  o  changeset:   0:870a5edc339c
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     0
+  
+