Process: only close the read end of the pipe after reading the full content successfully

If we close the read end of the pipe after hitting an error (EIO for example),
the child process may be still running and will print more content into the write end of the
pipe. Such write to a closed-read pipe will cause a SIGPIPE signal and fail.

Potentiall a fix to rdar://74058113

Author: nkcsgexi

Sources/TSCBasic/Process.swift

@@ -611,6 +611,14 @@ public final class Process: ObjectIdentifierProtocol {
                     break loop
                 }
             case 0:
+                // Close the read end of the output pipe.
+                // We should avoid closing the read end of the pipe in case
+                // -1 because the child process may still have content to be
+                // flushed into the write end of the pipe. If the read end of the
+                // pipe is closed, then a write will cause a SIGPIPE signal to
+                // be generated for the calling process.  If the calling process is
+                // ignoring this signal, then write fails with the error EPIPE.
+                close(fd)
                 break loop
             default:
                 let data = buf[0..<n]
@@ -621,8 +629,6 @@ public final class Process: ObjectIdentifierProtocol {
                 }
             }
         }
-        // Close the read end of the output pipe.
-        close(fd)
         // Construct the output result.
         return error.map(Result.failure) ?? .success(out)
     }