Merge #257: integration test: Document incompatibility of --all-features

4430f61 integration test: Document incompatibility of --all-features (Tobin C. Harding)

Pull request description:

  And I always forget that the integration test crate cannot be built with all features enabled.

  Add a section to the README in an attempt to save poor future Tobin the time to work this out again.

ACKs for top commit:
  jamillambert:
    ACK 4430f61

Tree-SHA512: ebc303eebc72c34e9d2e1f7a0b0e9ef23e0a7e9f6d537484d06bc8feb41e5481cab61081ebbb3b29998861390229519f6406091cc084d08191c8f0d1612e2129

Author: tcharding

integration_test/README.md

@@ -7,6 +7,11 @@ enabled. However `node` allows setting the environment variable
 
 `BITCOIND_EXE=/opt/bitcoin-28.0/bin/bitcoind cargo test --features=28_0`
 
+## All features
+
+Note that this crate cannot be built with `--all-features` because of
+how the internal `v28_and_below` style feature gates work.
+
 ## Shell alias' for the impatient
 
 I have all the Core versions on my machine e.g., `/opt/bitcoin-28.0`