1 optional doctest failing in cmdline.py related to pandoc

[seblabbe]

As reported in 8.7.beta0 on sage-release:

sage -t --long --optional=sage,pandoc src/sage/tests/cmdline.py

yields:

**********************************************************************
File "src/sage/tests/cmdline.py", line 820, in sage.tests.cmdline.test_executable
Failed example:
    print(open(output, 'r').read() == t)          # optional - pandoc
Expected:
    True
Got:
    False
**********************************************************************
1 item had failures:
   1 of 253 in sage.tests.cmdline.test_executable
    [252 tests, 1 failure, 41.02 s]

The reason is that:

sage: open(output, 'r').read()
'.. escape-backslashes\n.. default-role:: math\n\n\n::\n\n    sage: 1+1\n    2\n\n\n\n\n'
sage: t
'.. escape-backslashes\n.. default-role:: math\n\n\n::\n\n    sage: 1+1\n    2\n\n\n'

CC: @sagetrac-tmonteil

Component: packages: optional

Author: Sébastien Labbé

Branch/Commit: f2579fd

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/27172

[seblabbe]

Branch: u/slabbe/27172

[seblabbe]

Commit: f2579fd

[seblabbe]

Author: Sébastien Labbé

[seblabbe]

New commits:

f2579fd

27172: fixing optional pandoc doctest

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

comment:5

LGTM.

[vbraun]

Changed branch from u/slabbe/27172 to f2579fd