update URL and document Nim bug blocking further genericizing cleanups (#3483)

beacon_chain/consensus_object_pools/block_pools_types.nim

@@ -236,6 +236,14 @@ type
     blck*: BlockRef
     ## The block associated with the state found in data
 
+  # TODO when Nim 1.2 support is dropped, make these generic. 1.2 generates
+  # invalid C code, which gcc refuses to compile. Example test case:
+  # type
+  #   OnBlockAdded[T] = proc(x: T)
+  #   OnPhase0BlockAdded = OnBlockAdded[int]
+  # proc f(x: OnPhase0BlockAdded) = discard
+  # const nilCallback = OnPhase0BlockAdded(nil)
+  # f(nilCallback)
   OnPhase0BlockAdded* = proc(
     blckRef: BlockRef,
     blck: phase0.TrustedSignedBeaconBlock,

beacon_chain/networking/network_metadata.nim

@@ -98,7 +98,7 @@ proc readBootEnr*(path: string): seq[string] {.raises: [IOError, Defect].} =
 proc loadEth2NetworkMetadata*(path: string, eth1Network = none(Eth1Network)): Eth2NetworkMetadata
                              {.raises: [CatchableError, Defect].} =
   # Load data in eth2-networks format
-  # https://github.com/eth2-clients/eth2-networks/
+  # https://github.com/eth-clients/eth2-networks
 
   try:
     let

scripts/find_unchanged_consensus_spec_files.sh

@@ -11,8 +11,8 @@ REPO_URL=https://github.com/ethereum/consensus-specs.git
 VALID=".*\\.\\(md\\|py\\|yaml\\|sol\\)"
 UNCHANGED_SPEC_FILES=$(comm -12 --check-order <(git clone --branch "${PREV_VERSION}" --config advice.detachedHead=false --depth 1 --quiet "${REPO_URL}" "${TMPDIR1}" && cd "${TMPDIR1}" && find . -type f -regex "${VALID}" -print0 | xargs -0 sha256sum | sort) <(git clone --branch "${NEXT_VERSION}" --config advice.detachedHead=false --depth 1 --quiet "${REPO_URL}" "${TMPDIR2}" && cd "${TMPDIR2}" && find . -type f -regex "${VALID}" -print0 | xargs -0 sha256sum | sort) | awk '{print $2}' | sed -e"s/^\.\///" | shuf)
 
-# One can use this to automate the search andreplace with a tool such as
-# https://github.com/kcoyner/rpl/ or just a find/sed combination, e.g.,:
+# One can use this to automate the search and replace with a tool such as
+# https://github.com/kcoyner/rpl/, or just a find/sed combination, e.g.,:
 URL_BASE=https://github.com/ethereum/consensus-specs/blob/
 FROM=${URL_BASE}${PREV_VERSION}/
 TO=${URL_BASE}${NEXT_VERSION}/