The history builtin may fail with "table is locked"

[huiyiqun]

Run history repeatly, you may get following problem:

~> history
Exception: database table is locked: cmd
Traceback:
  [interactive], line 1:
    history

if you pipe the output to count, the probability the problem happens becomes higher.

[huiyiqun]

@zhsj Use this instead for editor mode

~> $le:history 233
▶ 'ls -la'
~> each { put $@ } $le:history
▶ 'ls -la'

and maybe history builtin for script? @xiaq

~> elvish a.elv
Exception: variable $le:history not found
Traceback:
  [interactive], line 1:
    each { put $@ } $le:history
Exception: elvish exited with 1
Traceback:
  [interactive], line 1:
    elvish a.elv
~> cat a.elv
each { put $@ } $le:history

[huiyiqun]

However, the builtin history is still dangerous for it will fail whenever the table is locked.

[xiaq]

See: mattn/go-sqlite3#274

PS. Since this bug might indicate that we are using sqlite in a wrong way, I am not accepting the PR to remove history until this bug is fixed.

[xiaq]

Also, with history | each { }, this happens virtually every time on my machine.