Do not validate return code if set was successful

[VicDeo]

Description

Do not call verifyReturnCode for successful set operation.

Related Issue

Fixes #25692

Motivation and Context

According to http://php.net/manual/en/memcached.set.php Memcached::set has a boolean result,
but it can return false both for unsuccessful operation and when it is called with false as a value http://php.net/manual/en/memcached.set.php#92259

So there is no need to validate Memcached::set when it returns true.
Sometimes it misbehaves as in #25692

How Has This Been Tested?

1. install ownCloud 9.1.x ( into the following envronment:
   PHP 5.5.9 + php-memcached extension + memcached server

2. Add to config.php:

'memcache.local' => '\\OC\\Memcache\\APCu',
 'memcache.distributed' => '\\OC\\Memcache\\Memcached', 'memcached_servers' => array ( 0 => array ( 0 => 'localhost', 1 => 11211, ), ),

3. Perform an integrity check

4. Perform an integrity check once again

5. See "Exception":"Exception","Message":"Error 21 interacting with memcached : SERVER END","Code":0

6. Repeat 4 & 5 Several times

7. Apply changes from this PR

8. Repeat 4. and see that 5. does not happen any more

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[mention-bot]

@VicDeo, thanks for your PR! By analyzing the history of the files in this pull request, we identified @DeepDiver1975, @butonic and @bantu to be potential reviewers.

[VicDeo]

@PVince81 IMO backport is required as it affects upgrade

[VicDeo]

Jenkins's dead:
error: index-pack died of signal 15
fatal: index-pack failed

[PVince81]

Makes sense 👍

You might need to rebase to revive Jenkins.

[VicDeo]

@PVince81 rebased, tests are passed

[butonic]

👍 nice find @VicDeo

[VicDeo]

Stable9.1 #26826
Stable9 #26827

[SergioBertolinSG]

@VicDeo this can be tested using php5-apcu version 4.0.2 or it requires a newer one?

[SergioBertolinSG]

Ok 4.0.2 cannot be used, using 4.0.7.

[VicDeo]

@SergioBertolinSG I don't remember exact version but apcu is unrelated to the issue anyway.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.