Reproduction steps:
1) Open any project or create a new one
2) Set up keystore. Note: Keystore alias password must contain backslash character
3) Try building for Android device with Gradle build system
-- Notice that build process fails

Reproducible only with Gradle build system. Internal (currently deprecated) does not reproduce this issue.

Reproduced with:
2018.3.0a9, 2018.2.4f1, 2017.4.9f1, 2017.2.3p3, 2017.1.5f1, 5.6.6f2

Note:
Tested with quite a lot of other non alphanumeric symbols - all of them are working just fine