Error with GIT_ASKPASS_TOKEN when trying to clone repository in Android Studio

I try to checkout a repository from Android Studio 3.4.2 (Git 2.22). IN the Clone Repository dialog I provided the correct URL and pressed the "Test" button. The result is an error "Illegal value of environment variable value GIT_ASKPASS_TOKEN"

Any ideas what is going wrong? I can clone the repository from the command line but not from within Android Studio.

Here's the excerpt from the log file:

2019-08-14 12:49:27,463 [ thread 15] INFO - #git4idea.commands.GitHandler - [.] git version
2019-08-14 12:49:28,026 [unnerw.exe] INFO - #git4idea.commands.GitHandler - git version 2.22.0.windows.1
2019-08-14 12:49:28,041 [ thread 15] INFO - ea.config.GitExecutableManager - Git version for C:\Program Files\Git\cmd\git.exe : 2.22.0
2019-08-14 12:49:28,119 [ thread 15] ERROR - #git4idea.commands.GitHandler - Illegal value of environment variable value GIT_ASKPASS_TOKEN:
com.intellij.execution.IllegalEnvVarException: Illegal value of environment variable value GIT_ASKPASS_TOKEN:
at com.intellij.execution.configurations.GeneralCommandLine.createProcess(GeneralCommandLine.java:390)
at com.intellij.execution.process.OSProcessHandler.startProcess(OSProcessHandler.java:51)
at com.intellij.execution.process.OSProcessHandler.<init>(OSProcessHandler.java:44)
at com.intellij.execution.process.KillableProcessHandler.<init>(KillableProcessHandler.java:49)
at com.intellij.execution.process.KillableProcessHandler.<init>(KillableProcessHandler.java:57)
at git4idea.commands.GitTextHandler$MyOSProcessHandler.<init>(GitTextHandler.java:176)
at git4idea.commands.GitLineHandler$1.<init>(GitLineHandler.java:147)
at git4idea.commands.GitLineHandler.createProcess(GitLineHandler.java:147)
at git4idea.commands.GitTextHandler.startProcess(GitTextHandler.java:73)
at git4idea.commands.GitHandler.start(GitHandler.java:491)
at git4idea.commands.GitHandler.runInCurrentThread(GitHandler.java:439)
at git4idea.commands.GitImplBase.doRun(GitImplBase.java:157)
at git4idea.commands.GitImplBase.run(GitImplBase.java:125)
at git4idea.commands.GitImplBase.run(GitImplBase.java:100)
at git4idea.commands.GitImplBase.runCommand(GitImplBase.java:50)
at git4idea.commands.GitImpl.runCommand(GitImpl.java:54)
at git4idea.commands.GitImpl.doLsRemote(GitImpl.java:734)
at git4idea.commands.GitImpl.lsRemote(GitImpl.java:595)
at git4idea.checkout.GitCloneDialog.test(GitCloneDialog.java:37)
at com.intellij.dvcs.ui.CloneDvcsDialog$7.run(CloneDvcsDialog.java:370)
at com.intellij.openapi.progress.impl.CoreProgressManager$TaskRunnable.run(CoreProgressManager.java:727)
at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$2(CoreProgressManager.java:164)
at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:582)
at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:532)
at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:87)
at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:151)
at com.intellij.openapi.progress.impl.CoreProgressManager$4.run(CoreProgressManager.java:403)
at com.intellij.openapi.application.impl.ApplicationImpl$1.run(ApplicationImpl.java:314)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
2019-08-14 12:49:28,119 [ thread 15] ERROR - #git4idea.commands.GitHandler - Android Studio 3.4.2 Build #AI-183.6156.11.34.5692245
2019-08-14 12:49:28,119 [ thread 15] ERROR - #git4idea.commands.GitHandler - JDK: 1.8.0_152-release; VM: OpenJDK 64-Bit Server VM; Vendor: JetBrains s.r.o
2019-08-14 12:49:28,119 [ thread 15] ERROR - #git4idea.commands.GitHandler - OS: Windows 10
2019-08-14 12:49:28,119 [ thread 15] ERROR - #git4idea.commands.GitHandler - Last Action: Vcs.Checkout.Git

Thanks for your help

Dirk