Fix display of Box End after transpile in text drawer

[enavarro51]

Summary

Fix #14271

Details and comments

This fixes a problem when the text drawer incorrectly displayed the End of a Box after a transpile.

qc = QuantumCircuit(4)
with qc.box():
    qc.cx(0,1)
    qc.cx(0,3)

qc_ = transpile(qc, initial_layout=[2,3,1,0])

print(qc_.draw(idle_wires=True))

Now produces

         ┌───────      ┌───┐ ───────┐
q_3 -> 0 ┤        ─────┤ X ├        ├─
         │             └─┬─┘        │
q_2 -> 1 ┤        ───────┼──        ├─
         │ Box-0         │    End-0 │
q_0 -> 2 ┤        ──■────■──        ├─
         │        ┌─┴─┐             │
q_1 -> 3 ┤        ┤ X ├─────        ├─
         └─────── └───┘      ───────┘

[qiskit-bot]

One or more of the following people are relevant to this code:

• @enavarro51
• @Qiskit/terra-core

[mtreinish]

This lgtm, thanks for fixing this

[coveralls]

Pull Request Test Coverage Report for Build 14799279952

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• 9 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.01%) to 87.915%

---

Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/expr.rs	1	94.23%
crates/qasm2/src/lex.rs	2	92.98%
crates/qasm2/src/parse.rs	6	97.61%

Totals
Change from base Build 14753521295:	0.01%
Covered Lines:	74567
Relevant Lines:	84817

---

💛 - Coveralls

[jakelishman]

Thanks Ed - I just hit this exact same bug with other control-flow constructs while writing a new version of SabreSwap too, and it was making it hard to debug!

[enavarro51]

Always happy to help - for the easy ones...

[ElePT]

@Mergifyio backport stable/1.4

[mergify]

backport stable/1.4

✅ Backports have been created

• #14324 Fix display of Box End after transpile in text drawer (backport #14278) has been created for branch stable/1.4 but encountered conflicts