getGradleCommandLine should not use sh

[isker]

What Renovate type are you using?
Self-hosted, renovate/renovate:latest.

Describe the bug

renovate/lib/manager/gradle/index.ts

Lines 151 to 153 in 24a9e29

	} else if (gradlewExists) {
	cmd = 'sh gradlew';
	} else {

Renovate invokes sh but inside of the docker image, sh is symlinked to /bin/dash, which finds invalid syntax in gradlew:

$ sh gradlew
gradlew: 158: gradlew: Syntax error: "(" unexpected
$ cat -n gradlew | grep -C3 158
   155	fi
   156
   157	# Split up the JVM_OPTS And GRADLE_OPTS values into an array, following the shell quoting and substitution rules
   158	function splitJvmOpts() {
   159	    JVM_OPTS=("$@")
   160	}
   161	eval splitJvmOpts $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS

This bash syntax is not valid in dash. gradlew ought to be treated as executable and executed directly, I think.

Did you see anything helpful in debug logs?

 WARN: Gradle command sh gradlew --init-script renovate-plugin.gradle renovate failed. Exit code: 2. (repository=foo/bar)
       "err": {
         "killed": false,
         "code": 2,
         "signal": null,
         "cmd": "sh gradlew --init-script renovate-plugin.gradle renovate",
         "stdout": "",
         "stderr": "gradlew: 158: gradlew: Syntax error: \"(\" unexpected\n",
         "message": "Command failed: sh gradlew --init-script renovate-plugin.gradle renovate\ngradlew: 158: gradlew: Syntax error: \"(\" unexpected\n",
         "stack": "Error: Command failed: sh gradlew --init-script renovate-plugin.gradle renovate\ngradlew: 158: gradlew: Syntax error: \"(\" unexpected\n\n    at ChildProcess.exithandler (child_process.js:294:12)\n    at ChildProcess.emit (events.js:198:13)\n    at ChildProcess.EventEmitter.emit (domain.js:448:20)\n    at maybeClose (internal/child_process.js:982:16)\n    at Socket.stream.socket.on (internal/child_process.js:389:11)\n    at Socket.emit (events.js:198:13)\n    at Socket.EventEmitter.emit (domain.js:448:20)\n    at Pipe._handle.close (net.js:606:12)"
       }

To Reproduce
Steps to reproduce the behavior:

1. Generate a Gradle project with Gradle 3.4.1 (I don't know that a version this old is necessary but it's the version that generated this project's gradlew).
2. Try to use renovate/renovate:latest on the resulting project.

[renovate-release]

🎉 This issue has been resolved in version 19.62.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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