rhg: demonstrate that rhg breaks on non-generaldelta revlogs

Differential Revision: https://phab.mercurial-scm.org/D11880

tests/test-rhg-no-generaldelta.t

@@ -0,0 +1,29 b''
+
+  $ NO_FALLBACK="env RHG_ON_UNSUPPORTED=abort"
+
+  $ cat << EOF >> $HGRCPATH
+  > [format]
+  > sparse-revlog = no
+  > EOF
+
+  $ hg init repo --config format.generaldelta=no --config format.usegeneraldelta=no
+  $ cd repo
+  $ (echo header; seq.py 20) > f
+  $ hg commit -q -Am initial
+  $ (echo header; seq.py 20; echo footer) > f
+  $ hg commit -q -Am x
+  $ hg update ".^"
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ (seq.py 20; echo footer) > f
+  $ hg commit -q -Am y
+  $ hg debugdeltachain f --template '{rev} {prevrev} {deltatype}\n'
+  0 -1 base
+  1 0 prev
+  2 1 prev
+
+rhg breaks on non-generaldelta revlogs:
+
+  $ $NO_FALLBACK hg cat f -r . | f --sha256 --size
+  abort: corrupted revlog (rhg !)
+  size=0, sha256=e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (rhg !)
+  size=58, sha256=0cf0386dd4813cc3b957ea790146627dfc0ec42ad3fcf47221b9842e4d5764c1 (no-rhg !)