tests/test-hgweb-bundle.t

streamclone: also stream caches to the client

When stream clone is used over bundle2, relevant cache files are also streamed.
This is expected to be a massive performance win for clone since no important
cache will have to be recomputed.

Some performance numbers:

(All times are wall-clock times in seconds, 2 attempts per case.)

# Mozilla-Central

## Clone over ssh over lan
V1 streaming: 234.3 239.6
V2 streaming: 248.4 243.7

## Clone over ssh over Internet
V1 streaming: 175.5 110.9
V2 streaming: 109.1 111.0

## Clone over HTTP over lan
V1 streaming: 105.3 105.6
V2 streaming: 112.7 111.4

## Clone over HTTP over internet
V1 streaming: 105.6 114.6
V2 streaming: 226.7 225.9

## Hg tags
V1 streaming (no cache): 1.084 1.071
V2 streaming (cache):    0.312 0.325

## Hg branches
V1 streaming (no cache):   14.047 14.148
V2 streaming (with cache):  0.312  0.333

# Pypy

## Clone over ssh over internet
V1 streaming: 29.4 30.1
V2 streaming: 31.2 30.1

## Clone over http over internet
V1 streaming: 29.7 29.7
V2 streaming: 75.2 72.9

(since ssh and lan are not affected, there seems to be an issue with how we
read/write the http stream on connection with latency, unrelated to the format)

## Hg tags
V1 streaming (no cache):   1.752 1.664
V2 streaming (with cache): 0.274 0.260

## Hg branches
V1 streaming (no cache):   4.469 4.728
V2 streaming (with cache): 0.318 0.321

# Private repository:
    * 500K revision revisions
    * 11K topological heads
    * 28K branch heads

## hg tags
no cache:   1543.332
with cache:    4.900

## hg branches
no cache:   91.828
with cache:  2.955

#require serve

  $ hg init server
  $ cd server
  $ cat >> .hg/hgrc << EOF
  > [extensions]
  > strip=
  > EOF

  $ echo 1 > foo
  $ hg commit -A -m 'first'
  adding foo
  $ echo 2 > bar
  $ hg commit -A -m 'second'
  adding bar

Produce a bundle to use

  $ hg strip -r 1
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/server/.hg/strip-backup/ed602e697e0f-cc9fff6a-backup.hg

Serve from a bundle file

  $ hg serve -R .hg/strip-backup/ed602e697e0f-cc9fff6a-backup.hg -d -p $HGPORT --pid-file=hg.pid
  $ cat hg.pid >> $DAEMON_PIDS

Ensure we're serving from the bundle

  $ (get-with-headers.py localhost:$HGPORT 'file/tip/?style=raw')
  200 Script output follows
  
  
  -rw-r--r-- 2 bar
  -rw-r--r-- 2 foo