fix weird end-of-file bug by having downloaders use inotify to directly track changes

Cargo.lock

@@ -747,6 +747,28 @@ dependencies = [
  "hashbrown",
 ]
 
+[[package]]
+name = "inotify"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "abf888f9575c290197b2c948dc9e9ff10bd1a39ad1ea8585f734585fa6b9d3f9"
+dependencies = [
+ "bitflags",
+ "futures-core",
+ "inotify-sys",
+ "libc",
+ "tokio",
+]
+
+[[package]]
+name = "inotify-sys"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e05c02b5e89bff3b946cedeca278abc628fe811e604f027c45a8aa3cf793d0eb"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "itoa"
 version = "1.0.1"
@@ -1383,6 +1405,7 @@ dependencies = [
  "crc32fast",
  "env_logger",
  "futures-core",
+ "inotify",
  "log",
  "mime",
  "pin-project-lite",