Exception after 101 BED files uploading and mm10_1000.bed

```
2019-07-12 11:28:27.036 java[91729:8750427] Error retrieving mirror status for display: 1104977154
11:41:12.625 [nettyCallPool-4-2] ERROR ktor.application - Unhandled: POST - /rules
java.lang.IllegalStateException: Reading is not available in state Reading
at kotlinx.coroutines.io.internal.ReadWriteBufferState.startReading$kotlinx_coroutines_io(ReadWriteBufferState.kt:19)
at kotlinx.coroutines.io.ByteBufferChannel.setupStateForRead(ByteBufferChannel.kt:238)
at kotlinx.coroutines.io.ByteBufferChannel.access$setupStateForRead(ByteBufferChannel.kt:21)
at kotlinx.coroutines.io.ByteBufferChannel.lookAhead(ByteBufferChannel.kt:2874)
at kotlinx.coroutines.io.DelimitedKt.readUntilDelimiter(Delimited.kt:24)
at io.ktor.http.cio.MultipartKt.copyUntilBoundary(Multipart.kt:346)
at io.ktor.http.cio.MultipartKt$copyUntilBoundary$1.invokeSuspend(Multipart.kt)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:32)
at kotlinx.coroutines.DispatchedContinuation.resumeWith(Dispatched.kt:108)
at kotlinx.coroutines.io.internal.CancellableReusableContinuation.resumeWith(CancellableReusableContinuation.kt:83)
at kotlinx.coroutines.io.ByteBufferChannel.resumeWriteOp(ByteBufferChannel.kt:2210)
at kotlinx.coroutines.io.ByteBufferChannel.bytesRead(ByteBufferChannel.kt:865)
at kotlinx.coroutines.io.ByteBufferChannel.readAsMuchAsPossible(ByteBufferChannel.kt:426)
at kotlinx.coroutines.io.ByteBufferChannel.readAvailable(ByteBufferChannel.kt:559)
at kotlinx.coroutines.io.ByteBufferChannel.readAvailableSuspend(ByteBufferChannel.kt:593)
at kotlinx.coroutines.io.ByteBufferChannel$readAvailableSuspend$2.invokeSuspend(ByteBufferChannel.kt)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:32)
at kotlinx.coroutines.DispatchedTask.run(Dispatched.kt:233)
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:463)
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.lang.Thread.run(Thread.java:748)
Exception in thread "nettyCallPool-4-2" java.lang.IllegalStateException: Reading is not available in state Reading
at kotlinx.coroutines.io.internal.ReadWriteBufferState.startReading$kotlinx_coroutines_io(ReadWriteBufferState.kt:19)
at kotlinx.coroutines.io.ByteBufferChannel.setupStateForRead(ByteBufferChannel.kt:238)
at kotlinx.coroutines.io.ByteBufferChannel.access$setupStateForRead(ByteBufferChannel.kt:21)
at kotlinx.coroutines.io.ByteBufferChannel.lookAhead(ByteBufferChannel.kt:2874)
at kotlinx.coroutines.io.DelimitedKt.readUntilDelimiter(Delimited.kt:24)
at io.ktor.http.cio.MultipartKt.copyUntilBoundary(Multipart.kt:346)
at io.ktor.http.cio.MultipartKt$copyUntilBoundary$1.invokeSuspend(Multipart.kt)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:32)
at kotlinx.coroutines.DispatchedContinuation.resumeWith(Dispatched.kt:108)
at kotlinx.coroutines.io.internal.CancellableReusableContinuation.resumeWith(CancellableReusableContinuation.kt:83)
at kotlinx.coroutines.io.ByteBufferChannel.resumeWriteOp(ByteBufferChannel.kt:2210)
at kotlinx.coroutines.io.ByteBufferChannel.bytesRead(ByteBufferChannel.kt:865)
at kotlinx.coroutines.io.ByteBufferChannel.readAsMuchAsPossible(ByteBufferChannel.kt:426)
at kotlinx.coroutines.io.ByteBufferChannel.readAvailable(ByteBufferChannel.kt:559)
at kotlinx.coroutines.io.ByteBufferChannel.readAvailableSuspend(ByteBufferChannel.kt:593)
at kotlinx.coroutines.io.ByteBufferChannel$readAvailableSuspend$2.invokeSuspend(ByteBufferChannel.kt)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:32)
at kotlinx.coroutines.DispatchedTask.run(Dispatched.kt:233)
at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:463)
at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.lang.Thread.run(Thread.java:748)
```

Start at the POST /rules multipart-upload path and inspect the Ktor Multipart.copyUntilBoundary call shown in the stack trace. Reproduce the failure with 101 BED files, including mm10_1000.bed, and confirm that the upload no longer raises the reported IllegalStateException.

Written by the indexing model from the issue text.