test-obsolete-bounds-checking: make the test compatible with chg

This test fails when run with chg because the error message starts
with "ProgrammingError" instead of "mercurial.error.ProgrammingError".
Therefore, globing the "mercurial.error." to ensure that the test is compatible
with chg.

Test Plan:
Ran the test 'test-obsolete-bounds-checking.t' with and without the
'--chg' option.

Differential Revision: https://phab.mercurial-scm.org/D1127

tests/test-obsolete-bounds-checking.t

@@ -1,23 +1,23 b''
 Create a repo, set the username to something more than 255 bytes, then run hg amend on it.
 
   $ unset HGUSER
   $ cat >> $HGRCPATH << EOF
   > [ui]
   > username = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa <[e-mail]>
   > [extensions]
   > amend =
   > [experimental]
   > stabilization=createmarkers,exchange
   > EOF
   $ hg init tmpa
   $ cd tmpa
   $ echo a > a
   $ hg add
   adding a
   $ hg commit -m "Initial commit"
   $ echo a >> a
   $ hg amend 2>&1 | egrep -v '^(\*\*|  )'
   transaction abort!
   rollback completed
   Traceback (most recent call last):
-  mercurial.error.ProgrammingError: obsstore metadata value cannot be longer than 255 bytes (value "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa <[e-mail]>" for key "user" is 285 bytes)
+  *ProgrammingError: obsstore metadata value cannot be longer than 255 bytes (value "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa <[e-mail]>" for key "user" is 285 bytes) (glob)