test: generate the `test-sparse-revlog` artifact when slow-test is allowed

The `test-sparse-revlog.t` logic requires a large bundle to be generated. This
bundle can be reused from one run to the next but its initial generation is
slow. With this patch, if the bundle is missing and slow tests are permitted,
the bundle will be generated during the test run.

This should ensure that CI run this test.

tests/test-sparse-revlog.t

@@ -1,136 +1,148 b''
 ====================================
 Test delta choice with sparse revlog
 ====================================
 
 Sparse-revlog usually shows the most gain on Manifest. However, it is simpler
 to general an appropriate file, so we test with a single file instead. The
 goal is to observe intermediate snapshot being created.
 
 We need a large enough file. Part of the content needs to be replaced
 repeatedly while some of it changes rarely.
 
   $ bundlepath="$TESTDIR/artifacts/cache/big-file-churn.hg"
 
   $ expectedhash=`cat "$bundlepath".md5`
+
+#if slow
+
+  $ if [ ! -f "$bundlepath" ]; then
+  >     "$TESTDIR"/artifacts/scripts/generate-churning-bundle.py > /dev/null
+  > fi
+
+#else
+
   $ if [ ! -f "$bundlepath" ]; then
   >     echo 'skipped: missing artifact, run "'"$TESTDIR"'/artifacts/scripts/generate-churning-bundle.py"'
   >     exit 80
   > fi
+
+#endif
+
   $ currenthash=`f -M "$bundlepath" | cut -d = -f 2`
   $ if [ "$currenthash" != "$expectedhash" ]; then
   >     echo 'skipped: outdated artifact, md5 "'"$currenthash"'" expected "'"$expectedhash"'" run "'"$TESTDIR"'/artifacts/scripts/generate-churning-bundle.py"'
   >     exit 80
   > fi
 
   $ cat >> $HGRCPATH << EOF
   > [format]
   > sparse-revlog = yes
   > maxchainlen = 15
   > [storage]
   > revlog.optimize-delta-parent-choice = yes
   > [format]
   > generaldelta = yes
   > EOF
   $ hg init sparse-repo
   $ cd sparse-repo
   $ hg unbundle $bundlepath
   adding changesets
   adding manifests
   adding file changes
   added 5001 changesets with 5001 changes to 1 files (+89 heads)
   new changesets 9706f5af64f4:d9032adc8114 (5001 drafts)
   (run 'hg heads' to see heads, 'hg merge' to merge)
   $ hg up
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   updated to "d9032adc8114: commit #5000"
   89 other heads for branch "default"
 
   $ hg log --stat -r 0:3
   changeset:   0:9706f5af64f4
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     initial commit
   
    SPARSE-REVLOG-TEST-FILE |  10500 ++++++++++++++++++++++++++++++++++++++++++++++
    1 files changed, 10500 insertions(+), 0 deletions(-)
   
   changeset:   1:724907deaa5e
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     commit #1
   
    SPARSE-REVLOG-TEST-FILE |  1068 +++++++++++++++++++++++-----------------------
    1 files changed, 534 insertions(+), 534 deletions(-)
   
   changeset:   2:62c41bce3e5d
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     commit #2
   
    SPARSE-REVLOG-TEST-FILE |  1068 +++++++++++++++++++++++-----------------------
    1 files changed, 534 insertions(+), 534 deletions(-)
   
   changeset:   3:348a9cbd6959
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     commit #3
   
    SPARSE-REVLOG-TEST-FILE |  1068 +++++++++++++++++++++++-----------------------
    1 files changed, 534 insertions(+), 534 deletions(-)
   
 
   $ f -s .hg/store/data/*.d
   .hg/store/data/_s_p_a_r_s_e-_r_e_v_l_o_g-_t_e_s_t-_f_i_l_e.d: size=63327412
   $ hg debugrevlog *
   format : 1
   flags  : generaldelta
   
   revisions     :     5001
       merges    :      625 (12.50%)
       normal    :     4376 (87.50%)
   revisions     :     5001
       empty     :        0 ( 0.00%)
                      text  :        0 (100.00%)
                      delta :        0 (100.00%)
       snapshot  :      383 ( 7.66%)
         lvl-0   :              3 ( 0.06%)
         lvl-1   :             20 ( 0.40%)
         lvl-2   :             68 ( 1.36%)
         lvl-3   :            112 ( 2.24%)
         lvl-4   :            180 ( 3.60%)
       deltas    :     4618 (92.34%)
   revision size : 63327412
       snapshot  :  9886710 (15.61%)
         lvl-0   :         603104 ( 0.95%)
         lvl-1   :        1559991 ( 2.46%)
         lvl-2   :        2295592 ( 3.62%)
         lvl-3   :        2531199 ( 4.00%)
         lvl-4   :        2896824 ( 4.57%)
       deltas    : 53440702 (84.39%)
   
   chunks        :     5001
       0x78 (x)  :     5001 (100.00%)
   chunks size   : 63327412
       0x78 (x)  : 63327412 (100.00%)
   
   avg chain length  :        9
   max chain length  :       15
   max chain reach   : 28248745
   compression ratio :       27
   
   uncompressed data size (min/max/avg) : 346468 / 346472 / 346471
   full revision size (min/max/avg)     : 201008 / 201050 / 201034
   inter-snapshot size (min/max/avg)    : 11596 / 168150 / 24430
       level-1   (min/max/avg)          : 16653 / 168150 / 77999
       level-2   (min/max/avg)          : 12951 / 85595 / 33758
       level-3   (min/max/avg)          : 11608 / 43029 / 22599
       level-4   (min/max/avg)          : 11596 / 21632 / 16093
   delta size (min/max/avg)             : 10649 / 107163 / 11572
   
   deltas against prev  : 3910 (84.67%)
       where prev = p1  : 3910     (100.00%)
       where prev = p2  :    0     ( 0.00%)
       other            :    0     ( 0.00%)
   deltas against p1    :  648 (14.03%)
   deltas against p2    :   60 ( 1.30%)
   deltas against other :    0 ( 0.00%)